It's the difference between bumped up constant beam attacks that your mana can actually sustain, the low level spells.....versus aimed spells that gouge your mana and usually require you to charge to release, the higher level spells. When the higher level ones hit, they can pancake stuff and knock it over. When you miss, you're automatically on the defensive. And for those that like companions, it sort of breaks the 4th wall when you basically consign your companion to the same AOE spam you use to beat enemies. And since you're the only one with the power to kill your companion for the most part....yeah.
It's *mostly* to taste. Some might like the fact spells have to be aimed and have rail gun-like accuracy requirements, because that kind of balances their power. Others might feel that magic should be a little more reliable than that, and they end up slumming it with the lowest level, most friendly to use spells bumped up through perks and gear.
I think the only real statements you can stand by is that spells have scaling problems and they're finite. You don't get a huge selection in what they do or how they work, versus melee. So you're literally stuck with all Tier 2 Elemental Damage spells being that obnoxious "charge before shooting" crap....even though it seems like enemy spell casters can just chain that shit back to back. Ironically, magic seems far more powerful in the hands of enemy NPCs than in the hands of the player. If they dual-casted for knock back more often, they'd be insanely nasty.