Modeling terrorists as trying to kill as many people as possible strikes me as insufficient. In Terror and Consent, Philip Bobbitt models their aims as propagandistic, which feels more like the right angle---hence the focus on inefficient but spectacular killing.
Incidentally, I've expanded my above comment into an essay called 'Terrorism is not Effective' (http://www.gwern.net/Terrorism%20is%20not%20Effective).
http://www.gwern.net/Terrorism%20is%20not%20about%20Terror