So this isn't based so much on my own game-play experience, but more on my watch of other play-throughs. Some of the Cantrips available to Wizards & Warlocks seem pretty OP....when you consider that they can be used an unlimited number of times (from what I can see, at any rate).
Though I don't think that Cantrips should be as limited as spells, I do wonder if there should be a limit on how many times you can use a single cantrip within a combat encounter? If only to encourage players to change up their cantrip use during combat.
That said, maybe I am completely off base here, & everyone else finds the cantrip system to be fine. Either way, I'd be curious to hear the thoughts of other players