Here's the problem: to the people concerned with money, a delay is really expensive, crunch is far less so. On a AAA game like this, a delay can cost millions in development costs, but those people are working on salary, so 12 hour days just cost the company an extra meal and maybe a few employees they have to replace who leave because of the crunch.
Then you come to the workers themselves, the people actually working those 12 hour shifts. They want to make the best game they can, and know that if they don't put in the time, the game will ship in a worse state, because it has the set milestone schedule. So many of them feel that they need to work the hours, even if it isn't required by management.