I believe it has been released early to compete with Age of Empires 3 for sales, as they both have roughly the same demography of players. I also suspect that some families who have their kids pestering them about Age of Empires 3 would tell the kids that -that- would be their Christmas gift, although its bought early, thus Firaxis might want to compete with that crowd and get a share, thus "hey, dont go for AOE3, CIV4 is also out get that instead as your early Christmas gift!". I do remember when I was a kid i just couldnt wait, i had to buy a game I like NOW even though another game that i might like more is coming out a month or two down the line.
As for the patch, Id rather have a patch now, and another one in 2 weeks. If im lucky it will fix my problem, if im not then what did i lose, im still gonna have to wait an extra 2 weeks now.
Usually the coders will test if a fix works, and then give it to the QA department for rigorous testing testing and testing on different platforms. Therefore the coders do not get "bogged down with testing", but move on to the next fix. At the end the whole package is tested again as a whole. This could be done for a few fixes and released now rather than a major update 2 weeks away.
As for the patch, Id rather have a patch now, and another one in 2 weeks. If im lucky it will fix my problem, if im not then what did i lose, im still gonna have to wait an extra 2 weeks now.
Usually the coders will test if a fix works, and then give it to the QA department for rigorous testing testing and testing on different platforms. Therefore the coders do not get "bogged down with testing", but move on to the next fix. At the end the whole package is tested again as a whole. This could be done for a few fixes and released now rather than a major update 2 weeks away.