I can see how this is unprofessional, but then again maybe it’s just my former military self speaking here. When in a uniform you arerepresenting your airline and/or pilots in general. Kids and such look up to you and may just want to say hi so they can be all happy for the rest of the day knowing they talked to a pilot. Secondly you are in uniform in your place of work, I know we are not information booths but people might want to ask a question or say something as we are “uniformed airline representives” so we should make ourselves available or take off the uniform if we don’t want to be available. (You know how the pager says if you see something please let security know or a uniformed airline representative)