Usually they just say so directly or did when the forums where hidden. They expressed openly multiple times they knew pvpers and raiders would hate covenants and wrote them off...
Then they remembered about a week after launch " o yeah we got rid of the old talent trees because players all ran identical builds....shit".
I don't think blizzard should use open forums for feedback but ignoring the players who understand the game better then they do is a massive mistake.
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They really shouldnt announce features until they are tested then. Even the ones they forced through like conduits were needed heavily into being bland choices and chores. If they can't be sure something shoukd be a hit...test first announce after.