How this turned into a shit thread I have no idea. I do sympathize with the OP being color blind myself. Nothing will come out of a petition I feel but worth bringing some attention to it.

Valve is aware of the issues. If you go into advanced options in the "HUD" area there is a colorblind mode. So when they coded they did think about it.

Yellow wouldn't come out to well I think on the map but a yellow vs. black would really stand out for me. I think if you looked though some colors may bring you out to much causing balancing issues with game-play.