I would say most of the younger PAP leaders speaks well. But since they are junior members, its not often that you hear them speak in Parliament.
However since English has been adopted as the first language, i believe that it would be good that all MPs speak the same language as much as possible. Of coz there are translators but it would reduce the essence of Parliament for direct communication between the MPs.
Just imagine if majority Chinese/Malay/Indian MPs decide to speak in their own language - there will be a feeling of racial divide.
Well, we are a pluralistic society; we cannot force them to speak in a language that they are very weak in. Imagine asking a MP who's well versed in hokkien and chinese to speak in international english; it wouldn't work as well.
That's why national TV has subtitles; in other countries, in a live audience, there will always be headphones for people who are not english speaking- say headphones for older Spanish-Americans who can't speak english- and a translator. So there are many other ways to reduce the feeling of a divide, and to perhaps bridge the gap.