I read alot of bad things about casting spells when you reach higher level, how you struggle.
Now.. Is there anyone else that can say they arn't struggling on Adept with magic at higher level and is having fun? If not, don't say a word.
Playing in Adept as well (default), level 31 Mage, light armor only, didn't power level enchanting or smithing either.
Haven't had any real problems.
Sure are enemies that take awhile to kill, but I can just "stun lock" them and they are rather trivial at that point. When a fresh Drauger Overlord Spawns and is stunlocked the entire fight, [censored] becomes a bit easy, lol.
Dual-casting lower level spells is how you play destruction magic. Its not about spamming Incinerate, its about dual-casting Fireball/Flame Bolt and lacking down enemies. Save those big magic attacks as single openers. Also, the "Wall" spells are incredible. Don't forget Frost Cloak...great against melee.
But struggling? Not even, I murder anything that comes up against me. Combine shouts, stuns, and AoE damage...yeah, my dude fears nothing.
Also, don't forget about the "Stones". I found an amazing one for casters, called the "Lord Stone". Gives you 25% magic resist, and 50 physical damage resistance (not exactly sure how that works)...really helped my survivability against multiple melee opponents.