+1
I'm afraid of this losing momentum because of misunderstandings again. So I want to stress this isn't about having access to the GM's art library. I don't need or want that. (In fact, I now have a whole mess of stuff in my library from the freebie Phandelver. It's a lot of stuff and that's just one game.)
It's about the players having access to their own. I totally get how messy it is when I have to upload the same token over and over. I once started deleting "duplicates" and suddenly they were disappearing off what I had in my vault. (That's even after copying the recently uploaded somewhere else in my library, so I don't delete recently uploaded anymore and now there's plenty of duplicates.) This would also be nice when I have several wild shape options and such like that.
I don't have a clue how difficult that would be. I also think it would be nice to be able to drag something from my art library over to another game. I never found a way to do that even when I was GM on both. (I had to do a screenshot of one, download it, and then re-upload it to the other game. That's silly.) But the ability to drag from one game to another might be difficult, I don't know.