When you finally get daedric armor it wont matter because you'll most likely be armor rating capped. So it's all about how you wanna look at this point, even though it's totally pointless since you'll play in 1st person anyway.

Design wise, daedra and ebony looks a lot better.... That's why.

System wise, dragon bones and scale are more common, light armor side have better perks, heavy armor can skip dragonplate, balance issue maybe?

Lore wise daedra armor always the best.

It′s actually quite simple: Daedra are awesome and Dragons are not.