I wish it didn't..
Me too. I'm likely swapping my main from resto shaman to another healer (although partly to make room for another person to play an ele shaman and still get all raid buffs covered in our 10 man).
As mentioned, you will want to 3 heal while you learn content and gear up. With a decently mobile healer like a priest and good instincts about when to move and where to position yourself you can get away with staying shaman. Druid will make your life easier though.