Lay of Hands
If we gave warriors (especially Prot warriors) an ability to cause 50,000 damage in one hit with no preparation on a 90-minute cooldown, most reasonable players would call that a balance problem. The long cooldown doesn't save it. Beyond some point you can't balance a very powerful ability just by increasing the cooldown.
Yes. Giving a lay on hands type ability to warriors would be over powered because they also have snares, interrupts, fear, gap closers and mortal strike.