For example, Jishnu, please give me some demonstration of exactly WHAT not allowing me to be sitting with things on my lap for the last hour of the flight is going to do?
I am not sure I or anyone can. As I said the initial reaction tends to be to prevent a repeat of the specific method, and various things are done with that in mind. It seems to me that this is consistent with human nature
IF someone wants to get through our security checks, they will do so. There are so many ways of doing so. XKCD posted a comic that is actually an interesting point- the average laptop battery, in its normal state with only a few invisible modifications, has the explosive capability of a small hand grenade. This is security theatre that pointlessly harasses innocent people. Investigations can be safely done without harassing innocent people.
Since you are such an expert I suggest that you offer your services to DHS/TSA to set them straight. It is always easy to rant on and on when no responsibility lies on your shoulder
So what concrete suggestions do you have?
I am the first to admit that many of the practices don't make any sens to me. But I also do not know exactly what objective test to apply to determine which ones are effective and which ones are not specially when the consequences of failure of anything is so horrible that one is unable to do experimentation to establish relative efficacy of techniques used.
Stepping back from the emotional aspects of this there appears to be two broad philosophies on which security of this sort is based. Basing methods on establishing the intent of a person at security checkpoints, which takes vastly superior and sophisticated training of the personnel manning such posts, is apparently the one used by Israel. Most of the rest of the world appears to use one which is based on establishing identity and preceding behavior of an individual with that identity. This requires less sophisticated training of security personnel, but the downside is that individual with same identity can change ones mind and start behaving differently after spending a vacation or two in NWFP/Waziristan. So then you have to establish exactly where one has been and whether one has gone through a life changing transformation in the process, which is not easy to do. Once you determine the inherent weakness, then one starts applying odd heuristics, the exact efficacy of which is hard to establish. This is what is happening at present.
Having been through the demonstrably efficacious (so far) Israeli method, which incidentally involves extensive profiling of each individual, I am quite sure people in the US would go completely non-linear if such were used across the board in the US.
Unfortunately the problem of terrorism in the sky is not one that can be wished away in today's world, and it is inevitable that some set of actions will continue to be taken with the hope of preventing as much mayhem as possible. Some will be effective and some will be just for show perhaps. But at the end of the day what else can one do given the nature of the beast? Gratuitously calling those that are operating in a difficult situation trying to protect lives, ****s and terrorist reflects more on the the ones making such statements and their juvenile idealism perhaps, than it adds to a reasoned debate and discussion of the matter at hand.