Why are there no good (original) open-source games?

Why are there no good (original) open-source games?
Anyone who knows me knows that I love open-source. If I could eat open-source software I probably would. If I could marry it then our children would be very odd. You get the idea.
There is something that open-source software seems to suck at and that is making good games. I play almost every OSS game I can get my hands on and the prettiest are graphically inferior to games from the average games of a couple of years ago, the audio is terribly mastered, the games are usually unbalanced and the stories are usually either ridiculously awful or involve Tux in some way.
Interestingly the freeware/mod scene on Windows seems to produce far better quality games than the open-source scene. I think this is because you where software fulfils a need for the user a game is a more creative act and needs a clear leader and a very undemocratic approach to aspects such as storyline and artwork. Games also tend to need to be “done” before they are released as no-one wants to play a story-driven game that just stops abrubtly.
I’m sure people are going to come onto this blog and complain that I’ve forgotten about all these great open-source games but I don’t really care. I’ve tried playing too many to find myself spending hours wishing I was playing even a poor paid-for game.
The only real exceptions I’ve found to the above rules are games which have been retroactively open-sourced such as Quake 3, Transport Tycoon, Tyrian and Star Control 2. These were all good games on release and open-sourcing them means they can be made more portable and keep being played for a long time. I highly recommend you check them