I don't begrudge Hikki her fame at all. In her own right she's a fantastic singer/performer, but she just doesn't have what it takes to keep me interested for long periods of time. I think it was GOOD for Ayu that she had the competition in Hikki though, and vice versa. I believe it helped to drive up both of there sales with fans either side wanting them to outdo eachother at points. This is mere speculation on my part of course, but i do honestly think it helps. Not only that, but with the two of them battling it out, it meant neither completely saturated the market, which in turn has lead to there longevity in the industry ^^.