I don't really think a class that can pick its fights at will has any business having this type of get of jail free card. Maybe a sprint of some sort but nothing that pulls them from combat instantly so they can redo their so called "openers" a second time on the same target.
Second reason you already can't target them until they open up and its asking too much telling people they need to reacquire the target that was just standing in front of them.
Third reason is these classes are supposed to lose prolonged fights with vanish they should NEVER lose a 1 on 1. They will simply leave and that shouldn't be so easy for them to do.
Just because it has been in other games doesn't mean it wasn't cheap in those games as well.