I have no problem with dolls promoting confidence, but I'd also like dolls to promote self respect too. Bratz, in my opinion, send the message that to have confidence you need to sexualize your appearance. There's a difference between dressing to put forward your best appearance, and dressing to display your wares to best advantage.
Maybe I'm just too idealistic

When I go out to nightclubs, I fully expect to see people dressed provocatively - we're not there to debate the merits of latin grammar

But teaching girls that confidence is dressing revealingly 24/7 as soon as they can wrangle their parents into buying the necessary 'cool' clothes? I haven't seen the cartoon so I can't comment on that.
I do love fashion, perhaps I'm just biased because my tastes are more conservative. As a child of the 80s, I loved my doll from the Jem cartoon series - I suppose those outfits weren't exactly conservative with their short skirts and heavy makeup, so maybe I'm giving too much credit to the influence plastic toys can have on children!