The pre-9/11 security screening itself was less invasive and faster than it is now. Luggage, bulky clothing, and anything that set off the metal detector still had to go through the X-ray.

A better alternative would be to let people keep their shoes on, stop worrying about liquids, and not scrutinize small objects in luggage that can't be identified, but obviously aren't guns or bombs large enough to crash a plane. Yes, people have tried to bomb aircraft using shoes and liquids, but those plots were not only ineffective but likely ineffectual.