They don't do subtitles because currently conference only has one feed that goes out to video, radio, and audio only streams. They're probably also factoring for the people that are not strong readers. I suppose in the future they could separate the feeds out; multiple subtitles and multiple language tracks?
Another note on overdubbing. Quite often in the past if a person speaks more than one language they will pre-record their talk in the other language (non-English in the past). When it's their turn to talk they overdub the audio with the pre-recorded version on that specific language channel so people get to hear the talk in the speaker's real voice, not the voice of the translator. Perhaps they could have done that in this case. If comfortable enough with English maybe they could have set it up such that Chi Hong Wong's overdub was in his own voice.
The people it really matters to aren't you and I so much, but the people that, for the first time ever, are getting to hear talks in conference in their native languages without being subject to the overdub. Now you can see what they've been dealing with for years.
