In this post, an Item Level Squish was proposed for ToC to make Ulduar more relevant. (blizzard did respond to this)
One of the biggest issues I have with retail and it started in Wrath was the fact that the next patch will completely invalidate anything you did previous by making all the previous gear nearly pointless to go for and thus making it almost pointless to do any type of raid outside of the current one, other than for trasnmog, a mount, title or achievement. I firmly believe that raiding should be a progression, that you work though the entire expansion.
Vanilla and TBC did catch up mechanics well, it gave you solid gear, but you still had a reason to go back and do previous raids. Even Karazhan was still worth doing for a fresh character that had access to Magisters Terrace.