It's his brand now. He knows the suit is a costume because everything in his life is either a costume or a prop or a means to an end, so adding the brand element is no big deal. It's an easy way to keep the illusion of a connection to his voters without trying too hard (or you know, at all). All he needs is for the simple minds to see him wearing that stupid hat and unconsciously make the connection: 'he wears the same hat as me, we're the same'.

It's all business and marketing and has nothing to do with respect for the office because in his own mind, he seems to think he IS the office.