I would love to see a way to preview and test out a mount. There could be a new area like a little obstacle course/playground where you could run around, jump, and watch the mount idle, or there could be a one minute/30 seconds "equip to preview" function for mounts in the crown shop.
Not relevant for mounts you can buy a one day version of for gold, but for the expensive crowns-only, or arena tickets mounts I'd like to know what I'm really getting.
I say this having been disappointed by more than one mount's walk cycle, and being leery of falling into the same trap again. I realize that kind of de-incentivizes the programmers to implement this (you make more money by tricking people into buying mounts they won't actually want to use; looking at you, Unicorn Courser ).
On the other hand, I'm hesitant to buy any new mounts because of this. Youtube reviews just don't cut it for me. I want to be in control, even if briefly, just to see what it's really like.