I've only put 60 hours into one character. With my first character I wanted to try out the dual wielding, so I decided to use swords. It may just be in my head, or idk, but it seemed like there was almost nobody wearing heavy armor or using magic. When I started using magic at about lvl 25 I started to see more spell casters. It's probably just all in my head, but I'm just asking to make sure.

I know for a fact that casters will cast spells aimed at your lowest resist from the very first spell they cast. So, if you have high fire and frost-- but no shock, you can be pretty much certain that they will be casting shock.

I don't doubt that the game also would send more dangerous melee types at casters-- or perhaps casters with certain magic resists if you are favoring certain elements in your own spellcasting.