I think Pape's argument makes perfect sense, but it goes only so far. From a tactical point of view, a suicide mission is a perfect solution, because it reverses the own-loss-to-inflicted-damage-ratio of a conventional combat operation. In the conventional combat operation, the attacking forces sustain much more heavy damage than the defenders. However, in a suicide mission this ratio is reversed - the "own loss" is limited to to a single individual, while the damage inflicted is dramatically maximized. Therefore, using this tactic by a weak force against a much stringer opponent makes perfect sense.
While Pape's argument does a good job explaining the motivation of the organizers of suicide attacks, it is not very effective in explaining the motivation of people of people who actually participate in them. It makes sense when, say, a villager from Guatemala or Iraq, whose family was murdered by the Americans or their henchmen, joins a guerilla group. But what motivates a second-generation Pakistani or Egyptian student or a social worker living in Amsterdam or London? After all, there were no Yugoslav terrorist attacks when the USAF bombed Yugoslav civilian targets. Besides, there are no US troops in Pakistan or Egypt anyway.
I think that my argument linking machismo and the hatred of "castrating" Western liberalism and feminism does a better job explaining that motivation. Please also note that this motivation dove-tails that of the terror organizers. The latter are motivated by tactical objectives of driving foreign troops out, but they need bodies to carry out their plans. The machismo cum hatred of Western liberal feminism motivates some to become such bodies.
Wojtek