It's not just the horses and their broken hocks, the riders slouch with their heads forward. In reality, these horses (and other mounts) would be accidentally throwing us every time we stopped due to the weight distribution and slouching.

Swimming mounts is v cool, but... they're not swimming 😅 very strange animations under the water.

It would be cool for personality based riding to be a thing.

Riding in houses for a show jumping course, or races.

Mounted emotes, so that you could have dressage (wouldn't work on some mounts).

And now that there's a variety of mounts coming to base game (and therefore this is no longer pay to win), different mount types should have different buffs
Things like
Horses faster over grass
Camels faster on sand
Ornaugs faster swimmers and on wet terrain
Vvardvarks faster in EP territory
Brekkas faster off road
Indriks faster in Summerset and Auridon
etc
No debuff to current mount speed, just buff.