Actually, out of ALL those groups you mentioned, KARA appeals more in Japan.
The japanese fans voted Goo Hara as the prettiest KPOP girl group member.
And they already had a fanbase in Japan way back in Rock U and Pretty Girl days.
You can watch Japanese girl groups (Morning Musume, AKB48) and see what I meant.
KARA has the style, voices and appearances that Japanese would like.
I don't see BEG, 2NE1 and WG being that successful in Japan.
Although SNSD can get attention too.
Don't underestimate KARA please.
No one said that they are #1 but getting this much attention proves something.