My extended family are from Malaysia. There are a lot of Chinese people there (my Dad was Chinese and was born only 200km away from where Wai Wong Ching grew up). The Chinese equivalent of a gary boy or chav is an "Ah Beng" (I am accused of being one sometimes by family members ), and somewhat predictably they have started importing the 500W / 1000W motors/conversions and riding these machines on the streets..
for those of you who have been to SE Asia and seen how mopeds are ridden, I'm sure you can just imagine the opportunities for collisions a widespread adoption of fast and moped-style e-bikes might lead to.. That said I doubt TBH the e-bikes will actually get banned, but simply held to the same standards we have in UK or EU..
here are some more articles there are also perfectly legal (by our standards) e-bikes in MY, not sure if its cultural reasons but the Malays (who are Muslim) seem to prefer these ones to the fast Chinese bike (there is at least one Malay company making them) although both cultural groups are coming together to protest any blanket ban and encourage sensible dialogue..