Hi, I'm new to the forums! I wanted to post my own thoughts on this, as I'm beside myself with excitement over seeing my all-time favorite character!
I don't see any babyish look to Peach's face. I think they're just making her look a bit more "realistic" while still keeping true to her roots.
I love the dress design too, by the way. She's certainly come a long way from the two-toned pink frock from the classic Nintendo years.