People who dress "nicely" to travel through airports, why?

I get that some people have business waiting at the pickup and wanting to look professional, but why everybody else?

There is a simple reason you haven’t considered.

I want to bring my suit on the trip, and I don’t want to crush it into a bag, because it’ll wrinkle.

LPT: You can roll suits and shirts in the bag so they don’t wrinkle.