Many people seem to be posting more or less the same questions in this thread that have been asked before. I'll therefore post roughly what I've said earlier.

No developer will want to be tied down to a definite date for the release of new software until the very last minute (usually the day before). This is because important bugs can be discovered during testing that would cause a delay - getting rid of some bugs can mean that several thousand lines of code would need to be rewritten. Even after the bug has been found and fixed, the game has to be retested to ensure that the fix works and that it doesn't have a "knock-on effect" on other areas of the game.

I'm sure that everyone would much rather have a working version of the game when it does come out than a version a week or so earlier that doesn't work properly or crashes. It is far better that no definite release date is advertised than it be postponed because of unforeseen factors.

That's not a guarantee that the released version will be bug-free - no software is ever that. There is always the chance that a bug will be missed by the beta testers, but will only surface when the game is played by a much wider variety of players and on a wider variety of machines. An example is the "generation 30" bug in Virtual Families. For that to have been found in beta testing the testing period would have to have lasted six months, which I'm sure no-one will agree is practical.