I'd certainly agree that if a quick fix starts to accrete complexity, that's good evidence that it's time for a rethink. "ad-hoc modifications", I'm less certain about. How often is this happening? How much effort do the modifications take? Would the modifications still be needed given a "done properly" version (my experience: often yes). Would they be substantially easier?

It can go either way, and I'm certain not trying to argue that quick fixes should never be replaced -- just that trade-offs should be considered.