On Release Dates and Developers Missing them

What is it with developers announcing release dates, getting their fans excited, only to delay the game a few months later? There's been quite a bit of that this year, but none of it really bothered me until it happened to a game I was very highly anticipating: Starcraft 2.

Someone correct me if I'm wrong, but developers aren't forced into announcing a release date, or even a release window, at least that I've seen. So why do they announce a timeframe that they know they can't make?

I understand that there are setbacks, such as Starcraft 2 and having to make it work with the new Battle.net (or so Blizzard says), but no one FORCED Blizzard into announcing a release window of 2009. I also get that developers may want to stake their claim in a slot to possibly ward of competition, but I don't see how it's worth it to do that if the developer is going to cut it that close and possibly compromise the quality of their product (I'm not talking about Starcraft 2 here, just generalizing).

When a developer delays a game, not only does it reflect poorly on the company, it also brings up questions about the quality of the game. Did something go wrong? What do they need that extra time for? Are they not happy with the product? Ultimately, because of the established history of delays,savvy consumers are less inclined to go out and buy the game Day 1. There may be exceptions to that with certain developers, but those developers aren't usually the ones making the delays in the first place. There is a distinct correlation between quality of the development team and the amount of delays their games have (as always, there are exceptions).

The bottom line: Don't announce anything about the release date, even a release window, until you are 100% sure you can make it.