The Guardian ran an article yesterday by Madeleine Bunting which tried to explain how suicide-bombing is descended from old tradition that Western Civilization has forgotten how to understand. (Thanks to John at Coldfury for the reference.)
"The west can only now kill from a distance - preferably from several thousand feet up in the air or several hundred kilometres away on an aircraft carrier. It is the very proximity of these suicide missions which is so shocking."
She needs to talk to some U.S. Marines on the ground in Iraq. I'm sure they're very familiar with the concept of killing the enemy up close and personal. And plenty of them would throw themselves on a grenade for their buddies. But they wouldn't be into committing suicide as a grand ideological statement.
So it's not the proximity. It's back to the ideology.
It's wrong ideas in the head
That make them long to be dead.