That Avi still gets me...
Anyway, I've noticed this too. I'm fine with it though as Rosalina is better than both Peach & Daisy. She comes off as having more personality. She has definitely picked up a large following and I'm sure Nintendo has noticed which is why she's appearing in more games.
Super Rosalina coming to a 3DS / Wii U near you soon? My guess would be yes. (or she'll play a much bigger role in the next 3D Mario)