The status of healer right now is more like an assurance more than a neccessity, yes you can finish most content without healer, but having them around will make more peaceful state of mind and faster the content to be finished since tank and dps can focus more doing dpsing rather than have to do mitigation or self heal, i use dps or tank if i want to be so focus on content and i use healer to be more relaxed, being healer i can see the mechanic easier since all my rotation is only 1 button most of the time