You can’t expect everyone to create unique stuff all the time. Coming up with truly unique gameplay is very difficult. It’s easier to reference to a popular game when explaining gameplay. I do that a lot when explaining the type of gameplay I want to my developers.
I do enjoy reading them, though. Everyone has a different thing they enjoyed from their favorite game and it’s good to know what it is. There’s also sometimes some hidden gold in someone’s creative thought process. Even a small thing like changing how a character reacts to damage could alter gameplay (ex. “what if instead of losing health, each hit adds percentage and the higher percentage the more they fly back”).
So from a strickly gameplay designer point of view, they could be useful even if they don’t always seem to be.