You just pointed out one of the problems. The class are designed for casuals and not for high tier players.
I think many problems come from this because Blizzard for some reason is not encouraging high level gameplay. If they leave the spec just like it is now, casuals will be perfectly happy and Blizz too.
The thing is that I don't see how designing the gameplay for high level would be a problem for casuals. I think only some tweaks would be enough to make the spec viable.
I know this debate has been around for a while but I kind of think it's one of the core problems.
As of now our gameplay feels good imo, but we still don't have anything special to bring to the raid ( except if our dps is op but probably won't happen). Even the awesome Windrush totem can be used as a resto.
Would you rather pick an average dps with only 1 utility or a good utility with other utility than only the totem. I think it's not hard to determine what's better.
The sad thing is that if it stays like this ,we'll just end up benched or we'll need to reroll just because our spec is utter garbage.
I just want my spec to be competitive at high level