Kill pots help loosen up the game. When a player must involuntarily put in 2 small bets preflop, his opponents may decide to loosen their starting hand requirements at the prospect of playing against two random cards for a big pot. This is a mistake, since it also costs more to enter a kill pot. The kill gives the illusion that you are entering a 3.5 SB pot for 1 SB, but in reality you're entering a 1.75 SB pot for 1 SB.

Consider this: the kill player is essentially posting the BB, and the BB is essentially posting the SB. However, the player holding the kill puck will often have good position. For a player with good postflop skills, a kill game against weak opponents can be very profitable.