What if you wanted to travel to protest the president, or the government in general?  What if you wanted to travel to attend an anti-abortion or pro-abortion protest?  What if you wanted to travel to attend a gun show?  

People might have legitimate reasons for wanting to travel anonymously.  Did you know that the TSA even infests the Lake Michigan ferry which crosses the lake and you have to present an ID to board a stupid boat?  Care to explain that?  Nothing to see here, move along.