3 things from me that are worth noting:
1: Every single system in the word is cheesable if you know it by heart or if find an exploit. Be it economic or a video game one. D&D was the same. Baldur's gate II was solable too. Especially with a mage.
2: Changing your spells on the fly is the only thing making it so you don't always stick to "the best spells". You won't rest just before meeting a group of enemies. But if I see a bunch of petrified drows i will go to my spellbook (as a cleric in this instance but the idea is the same) and change my spell to protection from evil cause something evil petrified them. I totally loved this interaction and I don't think it would be a nerf to anyone to remove it. It would only make weaker spells even more useless. Now at least i can use them if i see this 1 situation in which using color spray won't be a waste of breath.
3: -you get the only offensive spells in the game which can hit 100% of the time its target
Correct. Certain mage spells are just bonkers. Now...they are limited in use so that's why they are powerful. You can rest endlessly so that's why they are OP.
The only thing balancing mages is...the story line. The tadpole. You can't rest endlessly because of it. I know it's in stasis , bla bla bla but they already told us we will die in 7 days and it didn't happen. Now they told us it won't change us into mind flayers. Well...they might be wrong. Again.
