Really??? How many cleared Sunwell and Naxx 40 in comparison to the population? Last I check those were the 2 largest period of growth for Blizzard. And now that everyone can see the content, their population is steadily declining. History proves your theory wrong
Correlation is not causation.
Strange argument to bring up though, given that the most popular games on the market are generally considered dumbed down for casuals. It's clearly a rather successful strategy. (and no, I don't like it - I'm not a casual player at all).
If this were a solo game, I would love content as hard as pre-nerf DG. As it is, though, you need at least 7 other people to do ops, and most people have jobs and whatnot and simply don't have the time required to complete that level of difficulty. So for the sake of me ever doing such content, I'm happy it's easier. It's still bloody hard though. Anyone who says it isn't has a *very* unusual conception of difficulty.