Difficulty depends on content...
Most of the things added in 2.2 definitely ask DPS to pull their socks up. If you think Turn 8's gonna go down with your Monk flapping around at the flank all day or your Drg spamming Full Thrust...it ain't happening :P. All the story content is horribly forgiving, and the fights that really require you to fully know your DPS job are the optional end-game things (well, just second coil now, really)
I absolutely agree with them having the highest skill ceiling, as someone earlier in the thread said it seems there's always some way to squeeze out extra damage. Every time I think to myself I know my main job perfectly inside and out I'm always finding ways to improve. Those extra tidbits of damage aren't really going to make an impression or be that noticeable in most non-coil content, and some extremes I guess, but coil especially does a good job of separating the face-rollers from those who really know their job (or can at least read tooltips!)