... couldn't have said it better myself. I really think it's an ego thing.

What's missing from the list is one's SSN. (I suspect this is the case because a private company & not the government was asking for the voluntary disclosure of personal information.) On all REAL security clearance applications (Form SF-86), you're identified by your SSN. Given everything else on the list, I'm sure it's probably easy for the TSA to derive your SSN & that not directly asking for it was a clever way around the Privacy Act.

I suspect that a good portion of the 2400 sheelpe are the people you see running around airports wearing their ID's around their necks.

You're right -- pretty soon this will become "mandatory." Also, don't forget that the TSA left open the option of charging people for this "privilege."