I never understood the point of light armors in this game. Back pedalling and archery is not an option either way, it's not like being light on your feet lets you get in quick hits in melee combat (it's too slow in Skyrim for that), and they're hardly effective. If you're going to use armor at all I'd just use heavy armor

Tiber Septim got alot more than just access to ebony mines. The Tribunal also gave him the Numidium, which Tiber used to easily conquer the other provinces. But you asked what Morrowind got of the deal? They retained their identity. Look at Skyrim now, they are fighting for the right to worship Talos. The Empire never imposed strict rules on Morrowind. The Dunmer just wanted to be left alone and for the most part the Empire held up their end of the deal.