It’s not about “damage”. Terrorism never is. It’s about instilling fear and an over reaction that will have people sympathetic to your cause. It worked during 911 and it’s working right now in Israel.
Yeah, but that's my point. Planes go missing somewhat regularly, and sometimes even get blown out of the sky intentionally. It's news for a week or two. So why go through the trouble of getting on a plane and blow it up in the sky (and kill yourself in the process) when you can just blow up something like a music star's concert and get more media attention, and even survive the whole thing.