As a 10-man raider, I'm not a big fan of your idea. Just because I like raiding with fewer people doesn't mean I'm not looking for a challenge. Now, I am in a large guild, and we could probably put together a 25 man, but myself and the other raider who have taken on the responsibility of explaining fights to new people don't want to deal with the bull that 15 extra people bring to the table.

Personally, I love the concept of the hard mode. Remember, a blue has said that in Ulduar, the hard modes will in fact drop better loot. They won't just be for mounts, or for achievements and titles. You'll actually get better gear. Also, if your complaint is that "the raids are too easy", what should it matter if the hard modes drop better loot? The raid is harder, and that's what you've been complaining about.

It seems to me that the real complaint is "Everyone has gear." To me, the easiest way to fix this doesn't involve making Ulduar harder. The way to do it is to make whatever the new Archavon boss is only drop PvP gear, or drop PvE gear that's a tier behind. Right now, it's the first cycle of PvE. Yeah, cool, everyone gets some T7. I have no problem with that. But if it gets to the point that every fresh 80 in a bunch of greens can go kill, eventually, Archavon 4 and get Arthas loot? That's a problem.