Do you not think that terrorism is more effective when it is a spectacle? I think you wouldn't be able to ignite such visceral fears and reactions with almost any other kind of attack killing so few. The death of a skyscraper is more or less unheralded, and it's easy to empathize with the abject horror the people must've felt as that happened
If it's just a low-rise apartment in Anytown it's not going to drop everyone's jaw when played on TV. Can't believe people think my last comment was a commentary on the value of human life as opposed to the impact of literally toppling a tower...