So, a game mechanism that will be in the game for four expansions come Legion, that people like you have been whining massively about since before it went live, is not necessary?
No sir, you are obviously wrong. Blizzard would not continue to include such content against such opposition if their data told them they could get away with removing it.
Saying the game was at its most successful when it was harder proves nothing at all. That is mere correlation, and subsequent events conclusively show it there wasn't a causal link. The game was successful in spite of the end game being hardcore, not because of it.