I thought on this topic a bit more and I was reminded of what they did in WoW's Cataclysm expansion so I decided to expand on my previous post in this topic. In the expansion prior to that (Wrath of the Lich King), a moderately geared tank could pull an entire dungeon in roughly 2-3 trash pulls and by the end of it with the right gear I could pull an entire dungeon's worth of trash in 1-2 pulls and be in absolutely no danger of dying whatsoever. 8-10 minute dungeon runs were quite entertaining. In Cataclysm they dialed it back and made dungeons difficult again. They made individual enemies more dangerous, upped their damage, added priority targets that needed to be controlled and/or killed immediately, and spaced the pulls in such a way where in a few places you had to be careful since 2 groups of enemies meant death.

However, as you geared up through the raid content you sort of "graduated" out of needing to use crowd control and could just pump raw damage and aoe in to a group and even pull 2-3 groups at a time. I would be perfectly fine with the Cataclysm model, make the new dungeons legitimately challenging and dangerous but over time gearing up would make it easier to the point that once you did have that gear, you wouldn't need to be as careful. It's an interesting feeling when you can say "wow, I remember when this stuff would destroy me if I wasn't careful. I've really gotten stronger gearing up over time!"