What is the point of using quicken spell if the only thing you can use is cantrip?
A much better use of the point is to recover the slot, let alone other metamagics.
Nowadays, many classes are able to cast more than one spell per turn, and guess what? It is enjoyable to use the healing word and anything but the useless sacred flame.
Why is balance such a problem when it is a single player game?
If some things are too op, so be it if it makes the game more fun. It still won't be close to pathfinder and some builds.