I don't know a whole helluva lot about Nakamura but based on what I've seen, read and heard about the guy, he seems to be more charismatic rather than...hmmm...well eccentric? Is that the right PC word for Asuka?
Asuka is strange, though in an unusual, energetic sort of way and that does seem to go hand in hand quite a bit with a good deal of Japanese pop culture. She's bright, colorful, energetic and has sort of a vibrant strangeness about her. Not too change the subject, but does anyone else think she has a killer, sexy smile? It just seems that when she smiles during a match or whatever, she gets this sort of wild, gleeful look in her eyes when she smiles and is sort of the look that every guy dreams about seeing in the eyes of a woman. You know, the "I wanna rip your clothes off and ride you like a wild mountain goat" sort of gleam.
Nakamura seems more traditionally charismatic, or charismatic in the sense that's more traditional for American pro wrestling fans. He's got the goofy jacket, he's got the swagger when he walks, the mannerisms, and, from what I understand, she speaks English very well, so that in & of itself will go a very, very long way.
Of course, that's not to insinuate that what Asuka has is somehow bad, because it isn't. As I've alluded to, she has a colorful personality with a very expressive sort of style in the ring and uses her facial expressions to help convey a bit of a story. She doesn't look like a bikini or fitness model, which is what many Divas look like, and it translates well. Given that women's wrestling has finally started to mean something in the last 6 months on the main roster, a variety of different "types" of women are going to be needed just as there are different "types" of male counterparts.