I agree that healers should get more mounts, the current Unicorn isn't enough and also that's just a side quest, it doesn't recognize your contribution enough to healing regularly in duties.

Saying this it would be nice for every kind of sub-role to get unique mount a well, so one for melee dps, ranged, casters etc. I'd like to think it would encourage players to use other jobs more and learn their toolkits or what they can do, a little knowledge of other jobs goes far in party environments.