My problem with the expansions wasn't the fact that enemies had reflection, it was WHICH enemies had reflection. Goblins, Rieklings? Those are the common, unmagical enemies, I don't think they should have any magic-resistant anything (unless there were a wizard type of that creature).

But like people have mentioned before, reflection can be worked around. I took a pure mage through vanilla and both expansions, and yes, there were really difficult portions (the ones that were supposed to be difficult, like Clockwork City and Mortrag Glacier). Summon a whole bunch of creatures, go invisible and/or levitate away (at least in Bloodmoon), OR put some reflection on yourself (I'm not sure if it's supposed to happen, but if I and my enemy have reflect, if the spell reflects off the enemy it might reflect off me again and hit the enemy). Or you can buff up with magic resistance spells or shield spells if you know you'll fight a reflecty enemy. (For example I put a powerful fire shield on myself when fighting dremora lords). There are ways around every situation with magic. Destruction is not always the best answer.