I've wanted this since vanilla when I walked into the barrens and found I couldn't tame thunder lizards or kodos, always felt where other classes have a class specific mount hunters should of been able to tame these large beasts as a mount.
This is something I've wanted for a long time. Since a whole lot of the models (pretty much all beasts with 2 or 4 legs) are already made ready with animations for mounting and riding them this shouldn't be hard to implement. Call it bareback riding or something and they won't need to add a saddle to the models. And to counter the "then hunters gets easymode mount-achs" and such they could simply just make it not count as an ordinary mount but a spell and limit it to one mount at the time. If you 'tame' a new mount the old one disappears. This way it doesn't differ very much from the paladin/warlock equivalents already in the game.