I'm not going to blame Blizzard entirely for this. I am in fact going to lay much of that blame squarely at the feet of Beta testers. There was a lot of peacocking and 'git gud' attitude when trying to discuss things like issues Effigy; because it was offering a clear advantage, and the testers seemed to be picked from a pool who focused on min-maxing rather than the functionality of what was put in front of them.
There was also a very solid preference toward Destruction from most of those testers, either because they just preferred it for gameplay, or preferred it functionally, both of which led to a lack of testing and feedback for Affliction and Demonology. It wasn't just Blizzard ignoring them; the play testers did so themselves.
Sure, there were concerns raised, but largely in echo chambers and based on second hand information. I don't really blame Blizzard for not listening too hard to that, when the people in the testing themselves weren't overly vocal themselves and defending some of the problems that were being brought up - even if those defences were built on foundation of fear of losing numbers to changes. I wasn't in Beta this time around, and probably wouldn't and couldn't have tested much even if I was; but I've been in a few over the years and there has always been a strong defence of terrible mechanics in there when said mechanics have conferred considerable numbers advantages. People don't want to be nerfed - and by and large, for the people in Beta, the really hardcore players, ultimately it all comes down to numbers.