Here are my opinions about this.
I think the Vietnamese in Vietnam tend to not endorse this writing reform I guess because they're used to the current system, they simply think grouping words together is crazy and makes it hard to read. The Vietnamese oversea tend to endorse this polysyllabic writing thing I guess because they're exposed to English, Spanish, French, the romanized Japanese, Chinese, Korean...all write in polysyllabic and that must have had some influence on their perspective and opinion.
I will tell you this. It is true that Vietnamese isn't really a monosyllabic language. If I have to pick a term to describe it, I would say it's a
disyllabic one because most Vietnamese words, in order to obtain their contextual meaning, have to go in pair. Despite the seemingly monosyllabic nature of the language, Vietnamese almost never say anything in a single syllable. I'll give you some examples.
When Vietnamese want to say "fruits", they will say either "hoa quả" (literally "flowers and fruits") or "trái cây" (literally "fruit from the tree"). It would sound awkward if they say "quả" or "trái" alone, unless it's paired with another word, like quả táo (literally "apple fruit"), quả dứa (literally "pineapple fruit"), quả xoài (literally "mango fruit). So you see, even though one syllable is enough to represent the meaning of "fruits" or "apples", Vietnamese will almost never say them alone, they will pair it with another syllable.
Other examples are "nhà cửa" (literally "house and door") for houses. If we don't say nhà cửa, we say "cái nhà" or "ngôi nhà" (with "cái" and "ngôi" being classifiers). "Cây cối" (literally "trees and trees") for trees. "Trường lớp" (literally "school and class") for schools, or "trường học" (literally "school + learning/study"), and classes are "lớp học". "Bàn ghế" (literally tables and chairs) for furniture.
When we want to say "Humans are greedy" or "People are greedy", we use "con người/loài người" for "people/human". We don't just use "người". If you say "người thật tham lam", then "người" becomes a pronoun for "you", not a noun for human/people.
With a few exceptions of articles and prepositional words and pronouns...like thì, là, mà, nhưng (but), vẫn (still), những (plural indicator), cũng (also), thật, rất (really/very)...and a handful of adjectives. Vietnamese words usually go in pairs.
But nonetheless, I oppose this writing reform.
Why? There are many reasons.
1. Because average Vietnamese are not linguistics geeks. Because you're not supposed to impose something on a science level, a linguistic level onto the writing of common people.
Vietnamese people speak Vietnamese, but they don't dissect it and analyse every particle of it. Neither do the speakers of English, Spanish, Japanese, Chinese, Indian, Italian, whatever you name it. So changing a writing just for the sake of linguistics is absurd to me. Linguists can analyse a language, without disturbing the conventional writing of people.
Seriously, if you want to reform Vietnamese just for the sake of linguistics then there are a lot to change. For example, "chiến" should be written as "chiấn" because the offglide in this diphthong is an "â/ơ" not an "ê". "Anh" should be written as "Ayng". "Chiêu" should be written as "chiơu".
2. You're gonna complicate the matter with this reform. freeter pointed out the issue of "từ đơn" (simple word) and "từ ghép" (compound word). Well lots of times whether something is viewed as "từ đơn" or "từ ghép" is up to the perspectives of people.
Is "trường học" a compound word or two simple words? What about "theo đuổi"? What about "yêu thương"? What about "học bài"? Or even "bài học"?
You can argue that "học bài" is a compound word. But you can also argue that "học bài" are two simple words (học and bài). It depends on the perspective.
Then so many heated debates will spark over which are từ đơn, which are từ ghép. To go through all these debates just to determine how to write something, "yêuthương" or "yêu thương", "họcbài" or "học bài"... so much energy over something unnecessary.
3. Because Vietnamese is a very fluid language and it doesn't strictly adhere to any rule or regulation like Western languages. This reform will impose a set of rule, a set of regulation on Vietnamese, and it will change the fluid nature of our language. It will make Vietnamese become more rigid, more structured, and it will ruin free thinking and language creativity of our people.
Do you know why Vietnamese poems often sound better than English? Or should I say do you know why average Vietnamese compose poems more easily than average Westerners? (Well look at the enormous amount of folk poems that our people left, and even today composing poems is a common hobby of Vietnamese students, even though their styles are different). It's because of the fluidity of the Vietnamese language. It's because Vietnamese isn't bound by strict rules and regulations. The meanings of our vocabs are also very fluid. So Vietnamese people can freely express themselves in poetry without being limited by rigid conventions.
Do you know why they say "phong ba bảo táp chẳng bằng ngữ pháp Việt Nam?" It's not because our grammar is so hard. It's because our grammar is so fluid, because it's always changing from one situation to another, that it's hard to pinpoint any set of rule to teach foreigners. It doesn't mean there's no structure in Vietnamese language, but it's kinda a fluid structure that only people raised in Vietnam know and foreigners can't grasp.
When you make this reform, you're gonna make a set of rules and regulations on which are từ đơn and which are từ ghép. And by doing that you inhibit the free thinking and language creativity of the new Vietnamese generation. You're gonna make them think "theođuổi" is one word, and that they can't break down theo and đuổi and use those in interesting ways in combination with other words.
Given the fluidity nature of Vietnamese language, any word combination is possible. New words are generated by breaking down old words and make new combinations. What will happen if a student or a poet generates a new word? Do they have to go through the nuances if determining how to write it?
What if I want to take tinh from "tinh vy" and khôn from "khôn lanh" and combine them together and make "tinh khôn"?
Speaking of which, is "khôn lanh" a compound word or two simple words? Do you think of it as "khôn" (wise) and "lanh" (smart)? Or do you think of it as one compound word "khôn lanh"? It's really up to personal perspective. You see we can make countless debates on rules for từ đơn and từ ghép issues. Even the words "từ đơn" and "từ ghép" themselves can be a subject of debate. Do you think of "từ ghép" as a single compound word or two simple words?
But I guess none of the issues about new generated words would happen since people would be less language-creative anyway since we impose a rule on them, we tell them how to think.
You see, our language is fundamentally different from Western languages. Well for one, you can't break down syllables in most English words and combine them with syllables from other words to generate a new word. Well you can argue that they have stuff like biology, biosphere (bio+sphere) etc. But that's only for science and political terms, they can't really do things like taking "beau" from "beauty" and combine it with "fect" from "perfect" and make "beaufect" (for beautiful and perfect). But in Vietnamese, we do have things like "hoàn mỹ", which by the way can represent the concept of "beautiful and perfect" or "perfectly beautiful" or "perfect beauty" or beautifully perfect or just merely perfect.
So you can't apply writing norms in other languages to Vietnamese. You may ruin the very essence of the language itself - its fluidity.
4. It will make reading slower in my opinion. Some people argue that it makes reading quicker. Well yeah it's only quicker if you clear out the concepts of từ đơn and từ ghép as I said above, it's only quicker if you make rules on which are từ đơn and từ ghép, but there are many problems in trying to do so.
Seriously, average Vietnamese don't think much about which are từ đơn and which are từ ghép. So of course they're gonna spend time (like a few seconds), trying to figure out whether "pháthành" is phát hành or phá thành. Of course they're gonna figure it out, they're smart. But it's gonna take a few seconds.
It's like reading Vietnamese without diacritics, you'll figure it out, but it'll slow you down, it'll be never as quick as reading Vietnamese with diacritics. And really, I'm sure most Vietnamese don't want to go over process that freeter presented, that process of "oh phá thành are two từ đơn so this must be phát hành", every time they read a line or a paragraph.
5. As far as I know, the proposer of this reform did this at first not for the sake of practicality in Vietnamese, but because it helps him search for similarities between Vietnamese and other languages.
Like đôilứa is supposed to be similar to 我倆 wǒliăng
And chúngmình is supposed to be similar to 咱們 zánměn (we)
And cơngió is supposed to be similar to some Austronesian term for wind that starts with the k'

Yeah sure they look similar when you put them together like that

But it's ridiculous and I won't let others abuse this. The meaning of each respective syllable in a pair aren't even the same.
For example,
In chúngmình, "chúng" is the plural indicator, "mình" is the word for I, which btw came from "body".
In zanmen, "zan" is I, and "men" is the plural indicator.
You see, they're not even the same, but people are somehow able to make such ridiculous connection because the two syllables are written together.
That's the main reason why they started this reform proposal at first. It's ridiculous.
QUOTE (freeter @ Jan 21 2012, 02:36 PM)

Example: mênh mông (immense)
Mênh alone bears no meaning whatsoever. The word only exists when coupled with mông. Also, mông alone means butt (vastly different from immense). Hence, mênh mông is not 2 monosyllabic word but only 1 polysyllabic word.
You know well từ láy are special cases that can't be used to represent majority of Vietnamese vocabs. Từ láy happens when one syllable (which has a meaning) is duplicated, adding a second (meaningless) syllable that is similar to the first. When neither syllable has a meaning, it's an onomatopoeia or similar sorts.
Most Vietnamese words still make sense even when you break them down, even though they carry slightly different meanings. But
the meanings of those monosyllabic words are what make up the concepts behind the disyllabic compound words.BTW sometimes, a word in old Vietnamese lost its independent use and only appears in a compound word, leading us to think they're từ láy when the lost word is similar to the other syllable of the compound word. For example, Alexander Rhodes listed "trọt" as to plant in Vietnamese. Well in modern Vietnamese trọt doesn't have any meaning on its own, but it appears in "trồng trọt" which means to plant.
So trồng trọt is "to plant + to plant". Similar to "ca hát" (to sing + to sing). Theo đuối (to follow + to chase). Chạy nhảy (to run + to jump). Học hỏi (to learn + to ask). Thăm viếng (to visit + to visit). This way of combining words of similar meanings is very common in Vietnamese.