Yes, they can be. There was even once a time when we dragoons tamed our own dragons and rode them in battle.

[Less so now, with airships and the Red Wings, but even so, that's an important part of their legacy, not to be forgotten.]

It seems someone ought to have a talk with this Sorrow and find out what he knows. Unless that's already been attempted. Though... from what you're saying, and what I've heard, it's probably in the gods' best interest to keep us here.