I dunno, I can understand the motivation behind doing it, but to some onlookers like myself who can spot that stuff on sight, there is something "off" about the appearance...
First of all, the reason why they don't have the natural crease like occidental eyes, is because they lack the levitor muscle to hold and anchor the skin and fat up on the orbital bone. Also, that whole eye are is smaller, irises and all. It looks odd (IMO) to have all this unnatural whites of the eyes showing when the iris is still its small size (perhaps this is what spurred the over-sized contact lenses for "bigger eyes" in Asia).
There are very few things more beautiful than the natural elegance of the Oriental eye. So smoothly constructed, they rarely have the problems of "hollow eyes" when they age. The eye opening may be smaller than other people's but it has more beauty to me than a fake fold.
You know, I noticed more girls doing that in East Asia, but I have never met one American-born woman that does it. Different indoctrinations of what is beautiful, I suppose.