I'm not sure where this ID 'sacred cow' came from, but I think it was Congress immediately after 9/11 as one of their "do something, anything" reactions. It is tantamount to admitting that airport screening is not 100% (or close) to keeping weapons and explosives off planes, hence this layer(sic). I don't care who's on my plane so long as they are not armed, carrying explosives, drunk (or have BO); why does the government I wonder ?
I'd really like to know.
Well, as I speculated elsewhere, I believe in the next 3-5 years we'll move to some sort of registered traveler program in which screening will be greatly expedited, if not eliminated altogether, for participants.
The key to making this work is to be able to identify passengers with a high degree of accuracy. I believe what we're seeing now is TSA's attempts to "get the bugs out of the system" before any drastic, and potentially risky, changes are implemented.