Its skyrim, where the terrain isn't exactly as flat as Cyrodil. I'd figure most people would favor light, warm, and flexible armors than the Heavy, cumbersome, made of [censored]-freezing-metal armor.
I usually play the get up in your face warrior, but all I've seen in the videos is (what looks like) light armor.
Now, if they just have light armor, I won't complain. Its much more realistic for adventuring and whatnot.