Just bought some of the regular stuff (thus guaranteeing that the next bandit chief I see will be wearing it) and realized I kinda like that goat head sitting on my shoulder...but I do need the armor.
It was no ones idea. It was simply an oversight, got accidentally left out from the list.
There's a tremendous amount of bugs and missing functionalities in Skyrim. Unofficial patches fixes almost everything, even being unable to improve horn scaled armor, silver weapons, Wuuthrad and other uniques.
Besides using the patches, I've learned to restrain myself and don't play snoozefest simulator by smithing, enchanting and doing alchemy with every character. I find it much more fun to play with little to no crafting.