A single man fails in an attempt to blow up a plane with explosives in his shoes, we all have to take off our shoes at the airport now.
A single man fails to blow up a plane doing the same with his clothing, we all have to be frisked and body scanned at airports.
A group of foreigners plan and execute the greatest act of terrorism in U.S. history, suddenly Americans themselves are under suspicion and lose rights and freedoms.
A relatively tiny amount of people misuse guns, now everyone is in danger of losing rights.
People are sick of this. We have laws, and law enforcement in place to handle such things. When there is failure, the answer is NOT more restrictions for everyone. The answer is to be more efficient/competent, and recognize that a few people will always be selfish/evil.