Why not just melee on normal maps? Its more of a challenge, and fun
Probably because of the same reason why achiement maps pop up. If someone can cheat with no consequence, they will.
Plus, about the clientcommand switching to slot3 every 0.01 seconds. A fine idea, had it not been for the Sandman. When you're talking about a bunch of players with only melee weapons out, range > No range every time. Without the specific input to nullify the Sandman, the game will break fairly easily.