Even without access to the data Blizzard have we can see from Wow Progress that the number of guilds that have cleared HC Sha is extremely low and that even discounting alts less than 150k players (roughly 4% of the player base) have cleared normal Sha compared to just under 470k that have killed the first boss. Somewhere between the beginning and the end of the normal tier over two thirds of the players that have killed the first boss have given up on raiding I don't think we are in any position to say whether Blizzard are happy with the current rate of progress and there is a chance that they may decide the level of difficulty is currently too high and make the next tier easier.
That said I don't believe that there is any reason to delay the patch for a few thousand raiders.
This is an interesting point and I get the impression that Blizzard sometimes suffers from and is blinded by a need to be loved and that the management has not made the step up from a bunch of gamers to the leaders of a multi-million dollar company.