What's wrong with the new "enhanced pat-down" procedure at airports?

Let's begin by stipulating that, in the vast majority of cases, Transportation Safety Agency (TSA) employees are going out of their way to carry out this new mandate in as professional a manner as they can, given what they've been told to do.

That said, there's still something terribly wrong with enhanced pat-downs, from a legal and constitutional perspective. 

Behavior that would get any other law enforcement officer fired (and possibly jailed) is considered routine at these security checkpoints.  Search without probable cause or reasonable suspicion of any kind is illegal (and unconstitutional) in any other context.  What's the legal difference between this and a traffic cop randomly pulling your car over and, without a word, starting to rummage through your belongings, looking for evidence of wrongdoing?

In any other context, these pat-downs would be considered sexual harassment or even sexual assault, regardless of the intent of the one doing it, if the receiver did not consent.  I suppose that buying a plane ticket is supposed to imply consent.