It's always been our intent to offer new raid tiers in Cataclysm that are difficult to provide challenge to the raiding guilds, and then gradually allow older content to self-nerf as people gear up through VP, and then eventual literal nerfs to the content. That's something we've been communicating for some time.
Burning Crusade swung the pendulum one way, and Wrath of the Lich King swung it back too far the other. We're attempting to find that middle ground where there's still something brutally difficult for the cutting edge, but content gradually comes down until it's extremely accessible (ie PUGable) either simply through gear proliferation, or literal content difficulty nerfs.
There's always going to be two sides of the fence, some people want things more accessible for them and that's cool, we want it to be too, and some people think it should be difficult and always be that way because that's the way they had to do it. The fact of the matter is that as an MMO the end-game bar is constantly being raised, and progression content is in general not a place where we're going to purposefully gate prestige through difficulty. There are some exceptions of course, hard modes and unlock able bosses are purposefully there to be more difficult challenges, but as a whole our intent is to create a constantly moving ramp upward for Normal difficulty raids. That has to mean that the Normal raid content that was the hardest will one day be the easiest.
You will very likely see this same happen for Firelands when the raid tier above it is released. (Blue Tracker / Official Forums)