I have a question for all those that believe they should be able to dictate how others dress on an airplane. Did you pay for their travel? If not then, unless they are offending you in some way, and I don't just mean your sense of style, please mind your business.
Does anyone's company have a policy on dress code while on business travel? Mine does not, but I believe that some do. If one's company does have such a policy, then in that case I could see where the company may have a justification, as they are indeed paying for the travel.
Bottom line - if you didn't pay for my travel, please don't try to impose your arbitrary rules on me