I appreciate what KarmakazeNZ is saying, but you can't introduce psychological fear of death in a computer game very well. The "suppression" effect that "if they stick their head up they're dead" does not work. You can respawn, death means nothing. If you are out of ammo, it could be argued to be easier to simply blow yourself up with a grenade, or walk out into a MG line of fire, so you can respawn and get back into the action faster.
Obviously, that's not entirely true, but it illustrates my point. The fear of death is very minimal - you lose naught but a reinforcement point, a shave off your K
ratio, and 20 seconds or so of game time.
This is, in part, why I like CD. Death means you're out for a significant length of time. It SUCKS to die, so you avoid it. Of course, most people logging in are there for a FPS, so aren't up with these sorts of mechanics so CD never gets played.
Imagine that every map was CD, and when you died you lost all of your XP. How would you play then? (Also, you don't have the option to not play, since it is hypothetical
)
As a balancing factor, we could consider speeding up the XP gain 20-fold.