More than mount thenselves, I really really want to suggest:

- Give everyone an option for a slower pace speed (like Sleipnir). This should be given to all mounts as well as players on foot. It's very RP-friendly!
- Give mounts some animations when idle. You know how the Chocobo Companions look around when you're stopped? How come they just stare ahead like robots when you ride, instead? I'd like some life in these soulless mounts!
- Extend... bardings... TO ALL! The magitek could get painting themes to match the bardings instead!
- Final pipedream: can I had other mounts as companions? T-T