Whm should be the healer that should be easy to do good enough damage on, with decent optimization potential. Easy to learn, hard to master. The rest can stand to have harder skill floors, but considering whm is the only level 1 healer it makes sense for it to ease you into the role. That said, it still shouldn't be a 11111 job. That's just bad design, saying "we can let one of them remain badly designed" is lame.