Indeed, I actually do believe they need to stop adding jobs and fixing what they have but sadly one of the main draws are new classes. The only reason I bring this up is because healers are the only ones that have this problem. Any tank that is brought in can easily fit in cause they need to be able to do both ot and mt duties. Melees are just melees and same goes for casters. Phys range is admittedly also suffering an identity crisis. However for healers, we have the pure/shield split and so when they do finally add one, one of them is going to get shafted that expansion. Now, they could do it as something like one regen healer on expansion and then shield the next. That brings the issue of healers getting "favored".
At this point, it's a no win path they are at and hopefully when that time comes, they look over it. (Even though I have very little faith of them actually doing it)