Well, yes. I've seen a fair amount of casters who use evasion, but you're right, also many who use medium. Not so many with heavy, though.
Good on you. I suspect our experiences must differ, then, since I don't normally solo - we low man stuff, but I don't solo them. Maybe taking ALL the damage yourself make for a different experience?
For me, though, I haven't found that the MRR cap disadvantage normally outweighs evasion + huge dodge. Or maybe my experience is different since I'm normally a tankyish melee and you maybe play caster or something and can kite the physical attacks better, but are more often hit with spells?