I regret that people dress so sloppily on airplanes and in airports. 

A lot of people complaining about how the air travel experience has become so much less premium in recent years are the very ones dressed practically in pajamas. 

Comfort is not bad.  Suit and tie is not bad.  Sloppy is basically disrespectful to the people around you, for whom this trip is often the largest expense of the month or even year and who have no choice but to spend hours within inches of you.

I can't control what anyone else does, only myself and I can strongly influence my family.  For the past few years, I've made an effort to dress more presentably, or when on the company dollar, more professionally, when traveling.