10 man and 25 man are supposed to be roughly the same difficulty. The only difference is how many people you bring. 25 man drops better loot because co-ordinating 25 people is much harder than 10. 25 man should be tuned slighty harder but it won't be 10 man easy mode 25 man hard mode. A good thing in my opinion.

Blizzard has stated as well that Ulduar will be much much harder, (64 harder to be exact) than Naxx. However the days of wiping on a boss for months are over. The days of wiping on a boss on hard mode have begun. A good thing in my opinion. Now raids can tune the encounters to how good they are.

You want to have that pre-nerf mu'ru fight? Go for it with 4 pillars. Get yourself some ilevel 250 loot. Too hard? Try it with 3, get some ilevel 240 loot. Still too hard? Do it with 2. If your raid is good enough you can get yourself ilevel 230 loot. (I'm estimating the ilevels here, bear with me.) Do it with a pillar up get some ilevel 220 loot. STILL too hard? Alright, "faceroll" as you put it, your way into some ilevel 215 loot.

Another example, Hakkar lost abilities for each troll aspect you killed, but, correct me if I'm wrong, he dropped the same loot whether he had all aspects up, or none. Now, some guilds could have done it with no aspects easily. Don't you wish he had dropped more loot if you had done it with more abilities?
Replayability is the name of the game.
It's a good thing. A very good thing.

What I hope they don't do however, is continue to make mounts drop from the "hard modes". I find it funny that to get the best loot from sarth, you only need to do it with 2 drakes up. To get a drake, an awesome mount, (and believe me, I love mounts, I have an albino drake myself) you have to do it hard hard HARD mode. But the mount is still a vanity item. An awesome vanity item, but a vanity item just the same.