I really don't care what people wear on the plane as long as it's not indecent. A lot of people might need to go directly to/from work, so they don't have a choice.

To get special treatment, the airline employee has to give it (which is unlikely in 21st century airline travel). If it doesn't negatively affect me, I don't care.

Over Christmas, I was on a flight with a guy dressed in clothing that made it obvious he was a player or coach for an NBA team (looked him up later and I was right), plus the flight was going from where the team just played to where their next game was. It was obvious that for whatever reason he missed the charter and wasn't expecting nor did he recieve any special treatment. Just another business traveler.