Ultras, I think are something that should be considered. But there is something I think would benefit everyone. Each Race has an RSB (Racial Special Benefit). Therefore I thought these would be the ultra's in which were referenced. If I am wrong please correct me.
But before I get into the gore, I think some units should have an ultra. But two or three conditions must be met, in which research for that unit should be done, and only after full upgrades, can their ultimate be unleashed.
Second, the unit in question (Titans included) must meet a ultimate condition. For undead, it could be raise 30 skeletons, those skeletons become the titan's ultimate companion. Or maybe high elves would have merge 10 dragons into an ultimate dragon.
Anyway my two copper as usual.