The evidence suggests that terrorists care about influencing political outcomes. They are often motivated by geopolitical grievancesWell, holding strong political views or wanting to influence political outcomes is merely a symptom but doesn't explain why? Some of the causes might be occupation and oppression or what Krueger calls "geopolitical grievances". You must take into account what the Palestinian people have suffered and continue to suffer. These Palestinian suicide bombers were mostly from families in refugee camps since 1948 and their land, houses and farms taken over by Jews from Europe, America and elsewhere. They're harassed, jailed or even killed on a daily bases. Their entire existence is controlled by the very people who took their land, the Israelis. Could this be part of the cause? Krueger's article doesn't dwell into this, of course.
The article doesn't also go into the issue of defining who's a terrorist. To me, the American soldiers who tortured and killed prisoners in Abu Guraib were terrorists, and so are those of Al-Qaeda who're bombing civilians in Iraq. In the same token, what Israel does to the Palestinian people - and have been doing for the past 50+ years - is terrorism.