I agree with you on this one, and it's not only in SG we see it. Also other SE Asian countries have been westernised to some extend for the past few decades.
I live in Scandinavia (DK), and there is a small, but still significant Thai community here. There are also many men here marrying Thai women and they get children then who has grown up in Denmark for the past 2-3 decades. When I'm back home here in in my home country, I often have fun with local Asian boys and quite a few Thai boys, and here it's interesting (and a sadding too) to see what happens to Thai boys when they get exposed to western cultural ideas: The Thai boys who have grown up in 'pure' Thai families are still Thais inside - culturally and mentally - even though they are heavily impacted by the surrounding Northern European cultural mindset on sex, relationships and how to interact with other people. In bed, they feel like a "real" Thai boy if you can use this concept, but not as willing and curious and openminded as a Thai boy from Thailand.
The other group, the now grown-up kids of mixed Thai/Farang couples, are so westernised that it sometimes feels like it's only the look on the outside that is left of the general South East Asian culture and the specific Thai culture. Of course, if the couple had settled down in BKK instead of somewhere in Europe, it would be different. These boys are just as spoiled, annoying, arrogant, narrow-minded and sexually incurious and unwilling as average European boys. It's really sad to see.