No the problem currently is that because there is no entry level content they will have to nerf everything until its edible by everyone. Thats why they needed this additional zone. Content was tuned to the raid test team who have clearly become one of the best raid crews in the world atm, as would be expected. Nerfing things is just a poor way to solve a problem; yet sometimes...
Ill give my experience of WoW end-game from a MC+BWL+2/3 AQ guild which is vastly different view from almost everyone posting here from a deep Naxx (or cleared) guild.
The problem for us, the less skilled and dedicated raiders, could easily be solved with serious loot upgrades.
We don't have the same amount of playtime/dedication levels as the top guilds, hence we dont have all the items out of 5-man's/heroics, dont have all the uber craftable items that are already > T5 etc. We don't have the time to farm for mass consumable useage to make up for this lack of gear either - nor do we want to. Also, it takes us longer to learn a new encounter.
All the prior raid instances had a handful of "easy" bosses at the start of the instance (save Vael) ... I mean, any guild that took enough time could realistically clear Spider Wing and Raz in Naxx (we have done so with 25ish post-TBC). These easy bosses dropped FANTASTIC loot that made latter encounter substantially easier.
Top guilds hammered these bosses and had them all dead in the first few days (or hours) and where moving onto harder ones (say, Patchwerk). Of course, they didn't have the gear to do it as they had barely any loot thus far, so they make up the gap with mass abuse of consumables. Working as intended, I doubt anyone disagrees with this.
The lesser guilds took many weeks to kill these easier bosses, and did not have enough gear to take on Patchwerk. But because the gear was substantially better then what they had, they just simply farmed what content they COULD do inorder to gear up for it, in the process making already completed encounters easier. Eventually, after time, they had enough gear to beat Patchwerk etc.
Fast forward to TBC.
The loot is horrible - no massive upgrades as going T1->T2->T3 was. Karazhan has the "easy" bosses are the start with the harder ones to the end, but there isn't SUBSTANTIAL upgrades available in there to make the encounters trivial as there was in Vanilla WoW. The loot is marginal upgrades, so to get the same effect as ONE item from a T2->T3 upgrade you need 2-3 collective upgrades to get the same boost in raid effectiveness.
The only reason I can think of (logically) for the horrible itemisation is the PvP balancing between raiders and non-raiders (refer to the " PvP Balancing and the (adverse) effects on PvE endgame" thread http://elitistjerks....ad.php?t=10336).
If they took a look at the itemisation from TBC raid content and made them better then the 5-man loot it would make the raiding scene more accessable for casual raiding guilds. Make the T4 Equiv loot (Kara/Gruul/Mag) superior to all 5-man accessable gear ... it should hold the same degree of improvement as going from T1->T2 did.