Earlier quoted context omitted.
The goal of terrorism is to scare people into restricting their own freedoms. It has worked amazingly well so far. To any motivated anti-society organization or person, this is huge leverage. A few deaths leading to a noticeably more authoritarian state? What's not to love? It doesn't even matter if the authorities do their job and punish those responsible, the people will still choose to restrict their own freedoms…
To quibble: terrorism is using dramatic violence to achieve political ends. It just so happens that the victimized society often wants to increase security. The US had at least 3 major responses to 9/11: 1) seek revenge (invade Afghanistan, kill Bin Laden), 2) armor up (Dept. of Homeland Security), and 3) unify under nationalism (flags everywhere). It's pretty easy to imagine a timeline where some or none of those ha…
Suggestions that we shouldn't overreact because it plays right into their hands and that we shouldn't give up rights to the government out of simple fear that we'd just regret later didn't just go unheeded, they were vehemently attacked. It was worse polarization by far then we're seeing now, and it wasn't a more-or-less 50/50 split and didn't follow party lines.