I think casters kinda suck compared to warrior or rogue classes, but my problem primarily is with most utility spells being completely useless. I tried a kind of support caster in my first run using debuffs/buffs and stuff like smoke cloud etc., but I quickly came to the conclusion that it's not worth it to waste a turn on those spells, if instead I could be dealing damage.
IMO they should buff those non-damage spells, for example by making smoke cloud effect last for 1 turn after the enemy leaves the cloud, otherwise the enemy will just leave the AoE and can still attack in the same turn, rendering it completely useless...
