Allow me to clarify further your point.
Young asian civi girls with big tits in Asia are not necessarily embarrassed with their big boobs and most of them like their big boobs. But they are 'forced' to dress more conservatively in Asia. It is hard to get a big-boobed Asian girl to wear bikinis on the beaches in Asia too.
Asia is still conservative and young girls who dress in a manner that shows off their boobs tend to unfortunately attract a lot of pervs who like to 'stare' and/or follow them on streets as well attracting snide comments (she is cheap.., she is trying to sleep way up...etc) from their family and overall society.
So when these big-boobbed asian girls go abroad to N.America, Australia, or Europe for trips, study, work, they feel freer because they can wear the sexy outfits they could not wear in Asia. They feel safer in those places because girls with big boobs are not so much a big deal.
Whenever I see an Asian girl with big boobs wearing a bikini top or sexy outfit in HK, there is a very good chance that girl is not local but an overseas Asian from those places I listed above.
I do wish more big boobed Asian girls (local and overseas) wore sexy outfits as many do look so sexy.