I am a software developer at amateur level, I am writing a big piece of (virtual) paper for my university thesis and I have gained some experience during the years. I am not a pro, I do not get money (yet) for game development and I have tried a whole bunch of Operative Systems, and I don't take any part, my opinion is totally indipentent.
That said, I think it's not possible to blame game developers for the very few games that run on Linux. Consider that even on Mac there aren't that many, and as long as the system progresses the number of available game decreases. The problem is that it's quite harder for a company to write games for linux. If I want to make a very good game that costs me a lot (pay programmers, pay 2d/3d artists etc) I don't want to give the source obviously. And there isn't a real ALL-THE-LINUX_DISTROS standard for packaging. The available tools make development more nasty when it comes to games, in my opinion. Video Card drivers can't be shipped with the OS and this cause poroblems to users that can't install them theirselves... and this is a huge number of people that actually buys it.
Consider also that most of game developers uses directx that's not available on linux. I use OpenGL, but still I have some troubles time to time. Ubuntu 3rd party software can be installed like amsn, but this system is not a standard. Different distros takes different solutions, so it's hard to give guarantees. XGL gets in trouble with full screen, this is not a SIDE effect, cause many people still use XGL.
If there is no huge standardisation and no "betterment" of some tools, if there is no good solutions to driver, codecs and so on, if there is no huge innovation like a multiplatform great challenger of direct x (sdl is good but it's not possible to do the same things yet)... it is hard.
The big game on Linux was quake 3/4 but now seems (rumors) ID is completely joining Microsoft's side...
Summing up: standardisation, new clauses, more and better tools... linux people need to join forces at a distro indepindent level!
Possibly merging results like the ones ReactOS got could help...
Help game developers helping you!