Exactly! It's all about interactions. Now you are thinking out of the box, like me. They should be able to bring other entities back, eat insects, activate crystals with tongue (and switches with body), bring the hero from the other side of a long bad ground (the same with keys!), etc. That's the kind of ideas I'd like to use someday in puzzles. These things can also be used in minigames, to improve combat, and as easter eggs.
Unfortunately, we can't innovate too much in CoS, because it's mainly a remake of MoS-DX.