From the allowed list provided - which does not have a date, - there are a few interesting points: I cannot recall seeing any disclaimer regards equipment carriage, is it worth putting one on just incase?
Knitting needles, provided accompanied by wool.... OK thanks for the tip, so don't complete your woolly on sector one or your in trouble!
Religious items (ie Prayer Matt...) Could an IED be classed as a religious item when used in what certain people claim to be a religious war!
Seriously, as a former commercial pilot I've lived with ever increasing security for many years. The decisions have to be made very quick with limited info in a way that both protects the decision makers from blame if anything does happen while ensuring all security staff have a clear picture of what is required. Michael is quiet right that there is also the need to balance what can be done with the staffing resources. In the 2006 liquid case in the UK for a few days it was NO baggage at all. Even pilots could not take any hand luggage onto the flights except the flight paperwork, a pen and ones pilots license / passport.
It becomes a very black and white scenario for the decision makers even though the world is full of colour. Most folks do get along with just some additional time requirements - but there are always one or two security people who want to make a name for themselves in the same way some travellers insist of pushing the rules and then report back to the world on forums etc about how out of order things are.
I agree that some of the security appears theatre but in reality, despite at least 15 years of this kind of targeting aviation more than any other industry very, very little has succeeded. Remember hi profile Hijacks used to be fairly a frequent thing, but very little now. Most of what gets stopped never reaches any level of public news. It is easy to forget that at times - but I agree it is still a pain.
Weight of Hand Baggage - This become MUCH MORE CRITICAL when flying on smaller aeroplanes so while the chances of having it weighed on a 747 are low if your heading somewhere on a small flight in a repeatable airline then this will probably be part of the weight and balance calculations. Also if a flight is very full or close to the performance limits then individual weights may be required if suspected to be over the standard used weights.