That's funny you mention developers choosing DirectX for games as a design error.
Take for example Unreal Tournament 2004. For Windows it's a DirectX game.
HOWEVER, you have a small handfull of people, or maybe even one guy that worked for Atari and ported UT2004 to libSDL for graphics and openAL for sound.
I think that's funny. It works just fine in Linux. LibSDL and OpenAL are completely cross-platform (works in Windows, OS X, Linux, FreeBSD, etc). The libraries are staticly linked to the game binaries so there is no need to worry about versioning. Performance is good, I regularly kick windows-user's rear-ends online. The installer was a breeze, if I run it as root it installs in /usr/local/games if I install it as a user i stick it in /home/drag/apps/
No problem, no sweat. Ran into a couple problems with beta updates, but other then that it is just as nice as libsdl/openal as it is in DirectX as far as I can tell. Most mods work with little issue, all the user-built maps download and run just fine... etc etc.
i know it's off topic, but it's interesting.