CS players are idiots
Not true, I am a CS player. A lot of the population of CSS at the moment are very young, like kids who got HL2 for christmass or for their birthday when it came out because it was the latest top game.
If you find a decent server / clan you will see that a lot of CS players arnt idiots, they are competative but they still have fun.
I am one of the people who turned my brightness right up in the old CS versions so that I could see in the shadows (originally so that I could see in the militia tunnels when the lights were turned out and flashlights were disabled). Why did I do it? Becuase I care about winning that much? No, because other people do it and in turn you have to do it in order to compete.
Look at it like this; if your in a boxing match and the ref says you can put on a saftey helmet and your opponent does so, you would not be able to compete as effectivly if you didnt. Thus when you lost you would get annoyed and you wouldnt have as mutch fun. Counter-Strike is an amazing game with excellent gameplay, and thats why people compete on it so much. Because its fun to compete against other players to see who is the best and if you have a disadvantage (like having your brightness down) then it isnt as fun for you because you feel like you have been cheated.
I myself play CSS on the low graphics setting (not on low resolution though, that is a bit extreme) not because it improves my reactions (which it does, and is a handy bonus) but because I dont play games for the flashy graphics, and usually in CS you are concentrating so much on killing the other guy that you dont even notice all the graphics anyway. When I am rushing around in the levels jumping around corners and trying to get a flash bang away as fast as possible, I dont really notice or care about the HDR lighting that makes it that little bit "more realistic". Personally I think HDR lighting sucks, why the fuck do I want an iris effect in a game? Its ment to be a game, not real life. Also, as I said, its not the graphics that make the game, its the game itself.