At times I pondered creating a full fantasy RPG of my own.Originally I was thinking of this thread only in terms of spells that "ruin" exploration or become "must always prepare/cast" type spells, which as I said, is not an issue in my experience mostly based on my playstyle and current set of players.
But there are things that bother me, like. . .
I am not a fan of at-will cantrips (esp. damaging ones) at all. I don't think they break the game or anything, but aesthetically I think they undermine the "magic" of magic and make it into a repeatable infinite resource like a common sword and more reliable than arrows (which can run out)!
And in it, cantrips are in spells. You cast the spell and get a small selection of cantrips for 24 hours. To level the cantrip, you have touse higher level slots.
Casting Wizardy gives you light, mage hand, and prestidigitation for 1 day/slot.
Casting War Magic gives one offensive cantrip like firebolt or ray of frost for every level of slot you cast it at.
Classes based around cantrips would know the spells automatically and be able to cast it once for free.
This also means that half casters can snag cantrips if they wish to spend slots.
So your wizard can opt to save slots and run crossbows.
Or you can cast mage armor, wizardry,and war magic and have no spell lotss and only rituals at level 1.