I like to be able to jump for just for dicks sake in games, I don't think limiting the potential actions a player can make does anything really but annoy the player. Reaslism can be damned if I can't have fun, expecially in single player games.
Not to say I don't think its stupid how much jumping has integrated itself into games like CS and other tactics realism mods (ha, CS realism :p ) but the fact of the matter is, a crappyily physicsized jump is easyer to turn into whatever you want the jump to be for mod makers, than a jump that has lots of realism type stuff hardcoded into it. Think of how hard it would have been for flay to make skulks if the HL jump had issues like ground impact and what not hardcoded into it...
I say take out (or limit greatly, ala HI) jumping when it ruins gameplay, after all, there should be no reason for people to jump in combat in CS, IRL that will get you shot, fast, and you will be out of commission until long after you hit the floor. But there still is a a ting of action gameplay that we lose (leap over the railing, hop on the desk, mow down a couple opponents) when you remove jumping compleatly...