Well, if you listen to her voice during ZYX days and then listen to her current voice you'll notice she's improved lots. Her voice used to be very average and now it's totally the opposite: it's very recognisable.
About "fitting in the group", I noticed that aswell, her solo line in Meguru no Kisetsu sounded different. But the girls aren't 100% the ones to blame: if UFA tells them to sound less recognisable and more cute, the girls will have to do that.