I'm building my own systems to experiment with stuff and I started thinking about how this might stem from the player's specific targets and choices and how to encourage or even integrate that into a rule set. I thought if a player "makes an attack" and fails, the consequence could be anything so it's a bit too broad to think of something "appropriate" and/or cool. But if the player "tries to injure the creature's leg to cripple them" the possible consequences get more specific and interesting as well, don't they? It's the seed of an idea, but there might be something there.

@Ryan Childs I was thinking more of encouraging players to be more specific (I don't know how practical that would be) or choosing/creating a system that does. Maybe that way the fun consequences don't depend completely on the GM's improv or prep but are guided by the players ideas.