They are trying to prevent a bomb by keeping liquids off the plane along with the other new restrictions. They hope future analysis will discover effective less intrusive screening tactics. Wags have often suggested flying nude as an effective tactic. If all the bomber needs is a stealthy soda bottle, a disposable camera (plausible on such a flight) and brief privacy for the required final assembly, than embarking nude wouldn't stop the bomber. However, a very simple measure could stop the bomber, even without today's restrictions... Remove the doors from the planes' restrooms!
Folks might scream bloody murder, but it would prevent the murders and thus serve a higher priority. Without private restrooms there would be no on board assembly of stealth bombs, unless the majority on board were also suicidal Jihadis. They aren't stupid enough to try that strategy and most of us aren't stupid enough to join that boarding line. This could be preferable to another effective option - doing to the planes' restrooms what libs previously did to the planes' ashtrays. IMHO that option stinks. I'm not seriously suggesting this, but perhaps a less taboo way could be found to nullify this weak point in our security.
There's an even easier way than that. No muslims allowed to fly