Enchantments were much more rare* (and appropriate) in the games preceding Oblivion. And with enchanting as a skill armor typically could hold 1-5 pts of an enchantment while the best clothing could net from 80-120.
There might need to be a bit of tweaking (movement, spellcasting toll) for armor but it was not completely unbalanced before.
*Scrolls, though, were found a dime a dozen.
I've truthfully never played any TES games aside from Oblivion, so I wasn't aware of that. I think you're going in the right direction with that suggestion though. Maybe the degree of enchantment should depend on the quality of the item to be enchanted. See, an Iron or Leather cuirass shouldn't be able to be enchanted with something asinine like Fortify Health or Magicka 120 pts. However, 1 - 5 points is a lot more reasonable. As you go up in quality, you should be able to use greater enchantments.
I'd say that other pieces of armor, like gauntlets or helmets, should have a lower enhancement range, say 1 - 3 points or something.