I think you should have a special armour, only if YOU can design it.
If you want to design your own armor, your going to have to mod it in yourself, and if you can't do that, then you'll just have to stick with whatever armor is designed/
If you can forge weapons, why not forge armour?
I expect you can forge armor, but forging items doesn't mean you'll get to design them yourself, it's highly likely that you'll be limited to a list of items designed by Bethesda, albeit there may or may not be items that can't be acquired by other means.
Honestly, though, the Imperial Dragon armor was kind of pathetic as a main quest reward, it looked nice, but in terms of stats, it really wasn't worthy of being what you're rewarded with for saving the Empire from destruction, especially since if you weren't going out of the way to control your leveling, at that point, it would not be unlikely for you to be able to easily find much better armors in random loot. In Morrowind you also got a pretty weak item for defeating Dagoth Ur, but at least there, you could get some nice unique artifacts along the way, Oblivion doesn't benefit from that. The reward for completing the main quest should be something that's both unique and powerful, because when you've defeated a god to save the world from destruction, you deserve something good, I don't particularly care exactly what it is as long as it's something worthy of my deeds.