Alcohol isn't actually western, unless you meant that the specific beverages consumed by some Japanese youth are from western countries or just that alcohol is common for stress relief in the west, in which case I misread. It has been found to have existed in various parts of Asia for millennia (rice wine from about 7000 BC in China, distillation first recorded in India, etc.).
Well, it’s not supposed to be accessible to people under 21 in my state either.
One might say that most "design" concepts are there to escape reality (and quite a lot of "art"), by creating a substitute reality that's more pure and clear than messy reality. Both for practical (ease of use, readability) reasons and to increase sales/aesthetic appreciation. That's true for Kawaii as it is for Bauhaus or Flat Design.
i'd say that our [social/political/economic] reality is getting Kawaiized (that also dovetails with the recent simulacrum discussion), and that Kawaiization of reality is getting reflected in particular in design.
It first became popular in Japan, where there is also Hikkomori (adults refusing to leave the house), Grasseaters (young men refusing to date), and lots of fantasy harem videos on TV.
And now that the pressure increases in western societies, we see similar problems and similar escape mechanisms.
FYI alcohol is not accessible to people under 21 in Japan, thereby denying them one of the most popular western stress relieve drugs.