There are a few spells later on ( 2 source spells, which are geo/aero respectively, and 2 non-source spells, geo/aero again), who can cover quite a bit of the area fights happen in, so you either you're able to hit most enemies outright, or by simply standing in a strategic position which leads to enemies getting closer to each other as they approach you. Aero also gives you access to teleport, which makes things even easier.
The source spells usually lead to fights lasting a single round or 2 max, from the fights I've seen so far. At the point I'm currently, we have the problem that the friend I'm playing with currently plays 2 melee characters and is severely frustrated that he barely gets to do anything in fights.
But getting back to topic, yes, magic has a couple of problems. Nothing to do with the armour system, though. That has it's own problems, namely chain CC. The rest of it is "fine". Not great by a long shot, but fine. In terms of mages vs the armour system, I'm more frustrated by rarely having enemies being weak the the element I'm using, compared to the amount of fights every enemy has 50%+ resistance to whatever element I'm using and being basically useless.