I really don't understand what this debate is about, but then again as far as I'm concerned all spellcasters are spellcasters. Cleric, Druid, Wizard, Chanter, whatever, spellcaster. They're all the same class to me. They're usually funner to play than fighters because they get more options. If the class called 'wizard' is weak, I really don't care, and I don't understand why other people would care.
I don't really like damage dealing spells. They're boring. Divinity Original sin, I guess, did a good job of using elements and environmental effects to make attack spells interesting. With the help of awesome graphics!
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Casters need the ability to blind people, to trip them and knock them down, to make them unable to distinguish friend from foe, and to be able to cure or undo the effects of other casters. (buff and debuff in mechanical terms). They don't need the ability to actually do any damage.
Stealthies need to dance around the edge of combat, attacking units that have weakened in the behind, hunting casters, and using single target ranged attacks, occasionally getting sucked in by undistracted fighters.
Fighters need to bash each other in the face in an ugly mess in the center of the map while the casters and steathies dance around the outside, and the side that runs out of fighters first loses.
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But more important than all that! FAR more important! Everything needs to look cool. If someone is blinded, I want to be able to see it, the black cloud in front of their face. If someone is tripped I want to see them fall over and have to stand back up! If someone is grabbed by a vine, I want to see that vine crawl up his legs and grab his arms! If someone is suddenly glowing in the dark, negating their stealth skill, I wanna see them glow! If someone is frozen, I wanna see their hair turn white and frost form across their skin! If they're burned, I want to see them on fire!
You can make wizards as powerful or as weak as you want, if the spell animations and status effect animations are not there to support it, they'll just be boring.
So... make it look good! Make it LOOK good, make it look BEAUTIFUL! PLEASE!
Also make the fighters punching themselves and each other in the face look entertaining, please. That'll probably take a few hundred combat animations by itself.