This is the big question that a lot of people have, though most don't seem to understand why. Let me give you a situation:
You're waiting for that new, big AAA game to come out and you're told it's going to come out in September of 2012. As your anticipation grows, the deadline to the release looms closer and closer. Then, out of nowhere, the game is now delayed and pushed to December of 2012. That sucks, but it's not too long, right?
As that deadline too looms, you find that the game is delayed yet again, this time until next year in March! That sucks! Damnit! Why did they do it?? Well, I'm going to tell you why.
The truth is that most games (but not all) are actually completed long before their release date, so read on to find out the truth.
Corporations work on what's called a "Fiscal Year" and that is not the same as the actual year. Whereas we all live in January-December as our year, most corporations (Game companies included) will start their "year" in a random month, such as March. That means their company's "Fiscal Year" (google that term if you don't understand what it means) begins in March and that's when the Shareholders and those who own the company and provide them money look to forecast the future of the company's performance.
What happens is when that AAA title you've been waiting for in September gets delayed, it's more often than not (but not always, don't forget that) because of the "Fiscal Year." Allow me to explain. The company making the game, Company X, is releasing Game Y.
The game is set to release in September of 2012, and their next "Fiscal Year" begins in March of 2013. The company already knows they're not releasing the game in September, they had no intention of ever doing that. They needed to put that down as the date to entice people to keep their attention on it so they don't lose press coverage.
They always planned to wait until their next "Fiscal Year" to release it. The reason for this is because releasing a big-name game (or any game for that matter) that is going to be the most profitable will show Stockholders that they're set to make more money.
Now, you may be asking yourself "Well, why the fuck don't they just release it earlier? Why do they wait?" - Well, this I will explain as well.
When a company has a huge game they're releasing, a couple of things happen. First, this company is a Publicly Traded Company, which means they answer to Shareholders and they must show profits at all times. When Company X is set to release Game Y, they need to make sure that it aligns with their "Fiscal Year" to maximize profits during that period while not hurting their next "Fiscal Year."
What this means is if their "Fiscal Year" begins in March and if they release the game in December, that means they probably don't have another huge game coming in the next year to release during the next "Fiscal Year" to show that they're still making huge profits. The best thing to do, in their mind, is not release a game at the end of a "Fiscal Year" because any profits that are shown will only show up for the previous "Fiscal Year" because people would have already bought the game and sales will not stay strong 6 Months after a game is released.
Doing this makes their "Fiscal Year" starting in 2013 show a huge amount of sales and profit, thus carrying their company into the next year and boosting their companies values as well as Shareholders dividends and CEO's/Executives Paychecks. Of course, this fucks over the Consumer because they are forced to wait and wait for a game that all the while they're saying "needs to be polished" when in reality most games are done several months BEFORE their release date, but they need to coincide the release date with the "Fiscal Year" to meet the Publisher demands.
It seems very complex but it is all really simple when you think about it. It is all for profit, profit at the expense of the consumer.
Have you ever wondered why there are Day 1 Patches that they release? How can they already have to fix bugs? The reason is the same as I posted above and solidifies the truth: The games are already stamped and you can't go back and patch a Game Disc now can you?