Neither has Blizzard really nerfed the hardcore raiding philosophy into the ground nor there is significantly more challenging content coming down the pipe.
   When attunements were lifted for the first time in the Burning Crusade and Tempest Keep: the Eye and Serpentshrine Cavern were open to all level-70 raiding guilds. But those instances were in danger of going the same way Naxxramas did before the expansion: unseen by the customers who had paid for them. And that's just plain bad business.
   Naxxramas has been around a long time, which has been retooled a bit but there are Strats out there that have been out before even BC. Those Uber guilds spent the beta time practicing that raid over and over, just so they could say how cool they were when they cleared it.
We've cleared our share of bosses in there, but other bosses are right now kicking our teeth in and showing us that we are not ready. It's not like every guild out there is already "done" with Wrath. 
We want to point out the fact that there are more raids coming, and that Blizzard recently gave the hardcore a raid to their liking in Sunwell Plateau. Do the hardcore really think that they will be abandoned forever? Maybe there isn't a BT or a Sunwell in Wrath as of right now, but we're sure that Blizzard has some more difficult content to come. We already know that Ulduar is on the way, and it will be much more difficult just because it's completely new content. A new raid nobody has ever seen.
Keep in mind that only 5% of all raiding guilds had collected loot from Sunwell before patch 3.0. The numbers may have been even worse for Naxxramas. Strictly speaking, Blizzard probably lost money on Naxx before the expansion, because it only kept a handful of subscribers interested in the game. Molten Core, ZG, and AQ20 were far better investments in terms of maintaining the subscribers.
Those who feel entitled to enjoy nearly-exclusive content that has to be paid for by their fellow gamers. Some insist that only 5% of all raiders deserve to raid Sunwell because they put in the work that casual raiders often do not: farming for consumables, gear, repair gold, and then reading up on all the strats and repeatedly wiping on the trash on the way to the first boss and on Kalecgos himself. Unless the players are working for Blizzard or a game-review publisher, that's not work, it's just play that they may not enjoy very much. The only way to justify exclusive content is to pay for it with real-world money or real work. In fact, given the disparity of numbers, it would take an even bigger difference than that.
When the Burning Crusade was released, Gruul's and Magtheridon's lairs were very difficult for the top guilds and inaccessible to the rest of us. So, once enough of us got attuned, we ran Karazhan once a week, spending three or four nights on it and struggling until we'd collected lots of gear from there. This expansion is very different; you can run six raids without attunement and two more once you've cleared Naxx: a veritable purple rain. Purples drop in heroics now too. No wonder hardcore raiders could gear up so quickly and they have started to burn out so fast. The content is definitely easier, we haven't had to wipe a hundred times on any of these bosses, but Blizzard's business and games need to be fun for all of their customers.