I think gear has a lot to do with that. My raid group is starting to get geared out somewhat, ~5ish epics per person on average perhaps. The raids seem a bit easy now, though they were extremely difficult when we first started and I didn't even have 1 epic. Our MT went from ~140k hp to ~180k or something. We're only raiding one day a week atm, but we finally got to Valiona and Theralion last lockout and beat them on our 2nd pull, the only struggle numberswise being if people were a bit slow to move out of Theralion's void zones. Conclave of Wind doesn't seem hard at all even with very few epics, with the entire challenge being in the raid arrangement that is done before you pull... which I suppose is an indirect sort of challenge, actually. :p
I could talk about this more, but as was noted, we do tend to have a forum for this kind of stuff... :p Different kinds of difficulty (Naxx40 vs M'uru vs Conclave), the effect of gear (varies by fight!), changing roster, etc make it interesting stuff.
I have heard fairly decent things about Rifts, but I'm not expecting it to make much of a splash. And maybe I'm a child of The Vision™, but I tend to get a bit leery when devs make huge changes based on player feedback. I suppose it can work out alright, and definitely should always be considered, but I'm more inclined to trust devs with the longevity of a game than the playerbase on average. I think Final Fantasy 14 went through with similar sweeping changes and I haven't seen so much as a blip on the radar from that game. That doesn't implicate those changes, necessarily, but I did kinda expect more from that.
Ah well. Any MMO's success is a good thing for anyone in the genre, so even if I don't intend to play the game, I'd like to see some substantive quality to it.