There is no doubt in my mind that if Beyonce realized exactly what that comment would mean to us Singaporeans who have a command of English approximate to Queen's English, she would have never said it. Her comment was meant to flatter the enthusiastic Singaporean spirit, not to criticize it.
American brains are not wired to listen to Singlish. It is absolutely unintelligible to them. I personally use American enunciation when speaking to my American teammates for the simple reason that I do not want to waste their time (or mine) re-explaining what I had said. It isn't a matter of lack of national pride - I would NEVER give up using Singlish where appropriate - but simply a courtesy to other people in ensuring that I am expressing myself clearly. Remember those irritating girls in school who always spoke in pig Latin?
Most Americans have no problems with enunciating their words, but there are plenty of ang mohs who do. Here's an example you might relate better to: ever had to deal with a rambly Irish or Scottish old man? Their accent is THICK like you would not believe, but I'm pretty sure that they are speaking proper English.
The common Singaporean's problem is not just that Singlish-bred enunciation is bad; our actual command of vocabulary, grammar and syntax is poorly trained. Americans aren't necessarily better at the latter. In my experience, a lot of American kids have pretty poor English with horrendous typos and wierd grammer (hehe). In fact, if you asked Beyonce to write a formal letter by herself, chances are that her English might be pretty bad too. The key thing is that they don't sound like they speak bad even if their written English is bad. For many Singaporeans, they have a poor command of written AND spoken English, no thanks to our environment and lackadaisical attitude to proper English.
I completely disagree with the person who said that our command of English would be fine had we simply bothered to pay attention throughout primary/secondary school. Most people in this world have a tendency to write the way that they speak. Not all of us were "lucky" enough to grow up in an environment filled with only English speakers (ACS kids, I'm looking at you), so if one has to listen to a mish-mash of Mandarin, dialect and imperfect Singlish daily, don't you think that's going to spill over to the way we write? I believe this is true for a vast number of Singaporeans.
The "take it or leave it" attitude that Singaporeans have about Singlish strikes me as rather cloistered and almost xenophobic... IMO, Beyonce has already phrased it pretty gently; if your reaction to her is simply to clam up and slam African-Americans from 'tha hood' (which Beyonce clearly does not hail from, anyway), I am going to gently point you in the direction of Ris Low, and ask you to take her place on the international stage - then see what sort of comments YOU get.
I think Singlish should be enjoyed as a social and cultural element of our national identity. If other people don't get it, yes, that's too bad, but Singlish is not something we should be tooting our horn about as superior to the vernacular of other cultures. Neither should it be seen as inferior. It is indeed our own unique thing.
However, our civic responsibility is to avoid letting our country down, and by perpetuating the poor uptake of proper English (at least at the level required to execute business transactions), we are also perpetuating the image of "speaking poor English" that Beyonce brings up.