Hmm... I actually kinda prefer the new design. Not that MZT's design was bad, but the new one feels far more refined. I think maybe the issue why they went with the new one is because it felt a bit too similar to the Kongou-class sisters in Kancolle and they wanted one that was a lot more different.
I don't really mind she's a loli, though I get why some would've preferred her not to.