It has never been about real security. It's about the huge load of money that is funnelled through TSA who are set to spent it all, regardless of what they receive, on these magic wand devices or just angry personnel. Another reason is that security checks allow for arbitrary control of passengers. It's a powerful mechanism, just like a country with enough laws to make everyone guilty but where those laws are only enforced when "necessary", on a select few people. It's like legalized totalitarianism: all backed up by law and rules but the outcome is the same.