I kind of don't like how almost every Bandit Chief, Reaver Lord and Reaver Marauder you come across has Nordic Carved Armor. Sure it looks better than the old Steel Plate sets they would usually wear but it doesn't really make sense to me. I mean isn't Nordic Carved Armor supposed to be used by honor-bound Nords and friends of the Skaal instead of Bandits?

Welcome to half thought through leveld-list.
Play Morrowind if you want it to be more realistic or buy a PC with mods like REQUIEM or MORROWLOOT (but that won′t do the trick for nordic armor, i fear).

Better than them all wearing glass or even daedric.

Yeah you have a point. It was weird seeing Bandit and Marauder leaders wearing Daedric or Glass even though they were the rarest weapons and armor you could find (I'm not complaining, that was how I got a full set of Daedric). Nordic Carved Armor just doesn't fit Bandits though. Steel Plate and maybe Orcish makes more sense for Bandit Chiefs.