The problem is that our abilities are by and large designed to spin plates as opposed to allowing us to deal with various situations enemies can throw at us.
The difficulty of WoW should come as a result of enemies smacking you to pieces if you fail to respond to their attacks, or by them avoiding or minimising your damage, but instead enemies do very little and most of the time it’s just you fighting your own class trying to fire off 6 billion procs before they expire, or casting spells that do nothing to get the procs.
The fact that attacking a target dummy can be challenging for some specs is evidence enough that we’ve gone off the rails.
In PvP there’s a double whammy as both you and your opponent is creating tons of visual noise each from spinning their own plates. Once you’ve got an even moderately sized battle the server itself has problems due to it having to keep track of all the plates being spun.
This kind of gameplay was annoying since the day it came to be. It’s still annoying. It doesn’t improve the game in any way whatsoever.
The pruning should be all these little procs and CD’s and buffs going away and abilities being retuned to be much more dangerous in general and how tricky they are to use. We could use a small reduction in some cases elsewhere, but generally it’s all this rotation plate spinning madness that needs to go. 
I’ve commented on this myself many times.