There's a big opportunity in making current rewards more rewarding. There are more and more collectibles, but there generally are not many ways of using them nor showing them off. The development of mini games (like jousting for mounts) would go a long way.

A smaller order solution would be to have cases where players could display multiple collectibles at once, adding breadth to desirability and making for interesting combinations. One thing that could be done would be to add a special category of emotes that pull either randomly from your Non-Combat Pets or from those marked as Favorites.

I imagine the devs could come up with some fun ideas, so I'll just a put a few, and if anyone else wanted to think of some, that would be great!

-Summon two pets that face each other and play their animations at each other.
-Summon three pets that run around in circles chasing each other.
-Summon three pets that disappear into boxes, shuffle, and randomly reveal themselves.
-Summon three pets that float up in magic bubbles.

Hopefully that gets the vision across. Would be a fun way to be more engaged with collectibles. I could also imagine a ton of "summon one random pet and interact with it" types of emotes.