Good point; I agree. There are, however, forms of aircraft-targeted terrorism other than hijacking.
Agreed. Running luggage and boarders past explosive detection machines is probably worthwhile, and not much of an affront to customer dignity. Whether the passenger or luggage owner is identified accurately is largely irrelevant for this.
Expect most aircraft-targeted terrorism in the future to originate outside the aircraft. Weapons will probably be small ground launched missles or machine guns.