lol, when did the Kana thread suddenly become so dramatic? It's like one thing after another in here.
Kana's just doing what other JPop singers do: finding a niche that sells and sticking with it. It seems to me that most successful performers in Japan aren't overly concerned with "artistry" or trying to do everything and be everything with their music. It's like they figure "if I do 'this', someone else can do 'that', and music fans can listen to me when they're in the mood for what I have to offer and to someone else when they're not." It's just part of the conservative nature of Japan and its preference/appreciation of consistency.
Just my two cents.