Wouldn't you say that how a person dresses, whether travelling or any other time, says a lot about them? Some folks just aren't that concerned about appearance, some really are, as well as the shades of gray in between. The "are concerned" group isn't going to convince the "aren't concerned" group that something as trivial as what clothes to wear on an airplane is important. (I, myself, am the worst of the lot -- I really don't care, but I worry what those who do would think of me if I looked like the carefree slob that lurks inside me!)