I would say that there could be a situation where you have a choice to commit suicide while simultaneously killing your opponent OR by keeping both of you alive. This could allow your opponent to kill you on the next turn. Thus you not committing suicide prevents you from causing a draw if your opponent is in a better position.
"Doubt is not a pleasant condition, but certainty is absurd." Voltaire
Crafty Shaman Impersonator
I'm pretty sure the rule is there to prevent players from just crashing into someone they want to lose instead of trying to win. Also, a strategy in the game is to position yourself in places where others cannot force you off the board, and putting yourself in a position where your opponent dictates your next move, but all exits are safe, can often be helpful.