What difficulty are you playing on? I find it only to be an issue when it comes to Master or Legendary. The mid-range spells are available to boss-casters REALLY early and that can really screw you up. I tend to get 100 Alteration on melee characters purely for the 30% absorb chance of Atronach and the 30% magic resistance perks. It's well worth it if you can find a way to train.
I still play a Frost Mage that does the same thing to NPC's.
Any Mage that can cast an Adept Spell will cast it at least Once in Combat, and the Adept Spells all have an Area Of Effect. AOE Spells ignore Wards, and do not need to be accurate to be effective. The Frost variant has an "effect over time" added as the "cloud" passes opponents, which makes it especially effective.
I also use Alteration on all of My characters because the Perks have been responsible for My characters surviving Mages.
Not glitched at all -In fact, be glad he wasn't using lightning. Welcome to the level where the "stronk nord who trusts only in his steel" just doesn't cut it anymore.
Time to get serious son
Plus the fact that npc spells scale unlike ours which means they hurt a lot so he better start researching enchnating and up that magic resistance.
Ha ha. That made me laugh. Son, there are many methods to defend against mages- atronach stone, lord stone, alteration perks, potions of resist element, poisons of paralysis, wards, distract them with conjured creatures, use archery from a distance and float like a butterfly, or sneak attack those [censored]es!
If he's patient and doesn't want to turn to the cheapo crafting, just keep an eye out in the stores for magic resistance rings, and amulets. Do the quest in Riften for the temple of Mara and that will net you I think it was 15 percent magic resistance. There is also the lord stone if you don't mind taking it as your sign for an additional 25 percent. Should be able to stack enough resistance to take the bite out of enemy mages if you don't want to turn to magic.