However, when we migrated to 5e (we played in 2e to level 3, and we are level 4 in 5e right now), suddenly the flavor changed, epecially for the wizard, who was now casting spell after spell (ok, cantrip after cantrip, but in the game world, a cantrip is a spell), round after round. I know it may sound absurd, but we don't like that, at least not for this particular campaign. One of the things that, to us, evokes so much of the old school feel, is the strict resource management of magic, specially for wizards. Believe it or not, we actually like linear fighters and quadratic wizards, so to speak. I realized that limiting cantrips per short rest or per long rest would only solve the problem os possible exploitation, but would not solve the flavor problem.
I could simply take out all offensive cantrips and limit it to x times a day, and call it a day. But that would hurt the wizard a lot, as 5e class design was based on the assumption that (specially) wizards would rely a lot on offensive cantrips, besides the great reduction of the number of spells slots per day, compared to previous editions. What I am brainstorming is a way to remove cantrips altogether (leaving only the flavor ones), but at the same time, I have to try and be fair to the classes that rely on cantrips (specially the wizard and the sorcerer). How to do that is the big question. Removing cantrips and adding 2 more 1st level spells per day, would that be enough? Maybe more spells per day at higher levels as well?