Ever since Sept. 11 changed everything, airports around the world have introduced escalating inconveniences for air travelers. The Recess Supervisor had a good post on the subject last month.
Frequent travelers have coined the term "Security Theater" for the measures that are imposed on the public mainly to convince them something is being done. The ban on liquids was put in place in response to a specific plot to mix liquid explosives from components hidden in toiletry bottles. The outrage from flyers who demanded the right to pack toothpaste and shampoo in their carry-on bag led to the allowance for liquids in three-ounce, clear plastic bottles in a quart-sized zip-loc bag. The allowance makes the restriction utterly useless in preventing terrorists from smuggling liquid explosive components on board. So why are we being inconvenienced? To convince us that the TSA (and its counterparts around the world) can protect us from terrorists, so we'll be willing to travel by air.
In reality, the terrorist plots on airplanes since 9/11 have been foiled either by old-school procedures that were already in place, the sheer incompetence of the would-be terrorists, or quick thinking (and tackling) by flight attendants and fellow passengers.
If we really want to make people safer on planes, we should spend as much time giving them tips to spot and stop a terrorist as we do showing them how to use the oxygen masks and flotation devices on the plane. That emergency card tucked into the back of every seat should also include a list of suspicious behaviors and appropriate responses (grab the offender's hands and yell "Hey, what are you doing? Help!" to alert flight attendants and your fellow passengers to help you subdue someone who is trying to blow up the plane). The flight attendants can pantomime how to place a suspected terrorist in a bear-hug, right after they show us how to put on our life preserver in the event of a water landing.
This will be at least as helpful as restricting us to tiny bottles of shampoo. It has the added benefit of making the public feel empowered (and therefore, less easy to terrorize).