Debate fuels my Fire
Here are some better ways to limit spellcasting, without breaking the game:
Play in a setting in which public spellcasting is against the law. I've actually used this for a campaign. Sorcery was a crime and could only be done in secret. Convicted spellcasters received a brand on their forehead, forever marking them as criminals. Anyone with that mark could expect to be unwelcome in many places.
Give every spell a cooldown, forcing spellcasters to use varied spells, and not solve everything with the same spells.
Use Conans corruption system. Conan made spellcasting more powerful AND more dangerous. Each succesful spell, made the next spell even more powerful. But sorcerers risked corruption of their own soul with each spell. This rule makes spellcasters more conservative with magic use, and also makes them more fun to play.
Now these are some great solutions... using magic and immediately having the inquisition hunting you down, is a great story hook...