I really hope they are back. I wonder how much it costs to unlock the top part of the museum anyway
After reading your suggestions I've changed my mind :') I'm going to use them to store all the stuff I couldn't in previous games. So, I'll have a resident picture room, trophy room, model room (like house models) and a hybrid room sorted!
If there's four rooms...
1) Animal Photos! I'll probably put most of them in there, except for the ones I like the most :]
2) Hybrids! I might actually have the patience this time.
3) Clothing Boutique!
4) Gyroid Disco!!!!