> If it were Western looks influencing double eyelids, are guys also going blonde/brunette or doing anything else?
Absolutely, dyed hair is almost universally present amongst celebrities. Usually brown or red, but sometimes blonde.
You'll also see other surgically obtained Western facial features, such as a more elongated face and larger noses, in Korean celebrities. I'm not a facial structure expert so I can't scientifically enunciate it, but they don't look anything like your average Korean. For example, I wouldn't be surprised if they're modifying their foreheads too, to look like Tom Cruise in that picture you linked.
> In fact I honestly think (with enough grooming and styling) you can get more fit Asian guys looking like those two examples you gave than you could get white guys to look like them.
Oh, of course. No matter what you do, you'll never truly bridge the gap between races.
A good recent example of this is Cloud Atlas, which has drawn a lot of controversy for one of its story arcs, which is set in a futuristic "Neo-Seoul". Whereas the female actresses are Asian (Bae Doona of Korea and Zhou Xun of China), they used "yellow-face" to make male white actors look Asian, instead of using Asian actors.[0] Predictably, it's not at all a convincing makeover and has drawn harsh criticism from Asian American advocacy groups for the continued discrimination against/marginalization of Asian men by Hollywood.
> So just because of that, it's probably benefitting Asian guys more that they're being flaunted as sexy.
Right, and that's definitely the case. If you look at the expat blogosphere for Korea, what was dominated by men a few years ago is now dominated by women who write about their fairytale romances in Korea (no idea how true a lot of it is, but there you go)[1]. Either way, that's still a very small percentage of a very small percentage (remember that women like to blog about dating a lot more than men). And I'm just saying that obtaining Western features played a big role in the hallyu spreading to the West.
> As for Japan, they didn't have a well-developed live-action film industry
This is not exactly true. A lot of foreigners think that Japanese adults all read manga and watch anime, and while it is common to see salarymen reading manga on the train, its certainly not a widespread pastime the way that TV is in the West.
Japan does have a live-action film industry, but it's pretty shitty. The production values aren't nearly as high as in Korea (the sets look grungy, the background music isn't as good), the actors/actresses don't use as much plastic surgery/makeup, and they're not going for international appeal. Not to mention the acting/writing is even worse than in K-dramas, if you can believe that.
0: http://nerdreactor.com/2012/10/26/cloud-atlas-gets-heat-for-...
1: http://imnopicasso.blogspot.com/2010/10/myth-part-iv-awakeni...