It helps to better fire control, bigger stamina and actually every promotion raising all stats.
Also it depends on mode you play, you don't need only the kills like in DM, but in objectives mode, there is promotions just for staying alive, accomplish the tasks etc. On occupation I think it's then for kills and capturing flags.
So now you left h&d deluxe?? Or you just trying to play h&d2 multiplayer for the first time?
Camouflage is the colour of fear... I have no need to hide from my foes... I have no fear of death. My colours I wear openly, they proclaim louder than any words, "I am proud to live - I am proud to die".