The martyrdom angle doesn't play. An effective martyr has to have uniqueness. A couple hundred dead guys who blew themselves up don't have any pull as a unique, focal point for propaganda or to serve as a rallying point. It's just a couple hundred dead thugs.
From another angle, if the British had hanged a hundred school teachers as spies, it would have been an atrocity among many in war. However, one Nathan Hale saying "I regret that I have but one life to lose for my country" before being hung as a spy becomes a unique event - a rallying point.
There's no glorious martyrdom for another terrorist blowing themselves up. More would follow anyway since it is ingrained in the lack of culture. Much like gangbangers blowing each other away in central LA doesn't affect the number of kids joining gangs.
Terrorists killed in the War on Terror are completely reformed and have a 0% recidivism rate.