Yeah I think the whole submission system needs a revamp. When you've weakened a superstar's body part a few times you can easily make him tap out if you're using a finisher because it gets the added power to it which comes with a finisher. It's too easy and that's why I've tend to stay away from submission finishers in recent years.
I'm not sure what's the problem with this. Working on and targeting your opponent's leg and then using a submission finisher that targets the leg to make him tap sounds pretty logical to me, but they do need to put back holding onto a submission move after a rope break.