It's the standard in software development, period. If companies delay their games till all their bugs were fixed, the lack of revenue would probably have a negative impact on that project, as well as any future ones. Not to mention, limited Beta Test teams aside, alot of problems (both bugs and design flaws) are going to show up once you exponintially expand the player base with a release.
And, before we get all sentimental about the way things use to be, the number of games that release in an almost completely bug free condition are quite small. Some of Sid Meier's projects come to mind, and some early Microsoft-published games. On the other hand, most ambitious and complex history-themed games (sims and wargames alike) from any era of computer publishing, were chock full of bugs. I am think of, among others: Fields of Glory, American Civil War, Wargamer: Napoleon 1813, Great Naval Battles: North Atlantic, Falcon 4.0, and the list goes on.
I am not saying I like the fact, but I believe it is the inevitable price we pay for more complex games.
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