Addendum: to answer how to actually fix it, my best suggestion is to limit the number of cantrips you can use.
Perhaps something as simple as "you can cast a number of cantrips equal to your spellcasting ability modifier +3. You regain all spent uses after taking a short or long rest".
This might not change much from your perspective, but it does change the balance slightly (in the favor of spells over cantrips).
But mostly it fixes a personal bugbear of mine - how casters can cast Firebolt or Acid Splash all day long, every round for hours on end, and how this breaks world verisimiltude. Need to dispose of a corpse? Just dissolve it with an endless number of acid cantrips! Need to break out of sheriff's jail? Just burn a hole in the wall! After all, a "cantrip" than can kill a grown man in one or two blasts (a commoner), can't be said to have "no effect" on the environment! *blech*