The other reasons for picking a distinct mode of dress, aside from the dignified appearance of black and white, are several:
Separation from goyim – while according to most opinions, one does not violate the letter of the law of bechukosayhem lo saylaychu as long as they are noticeably jewish (yarmulkah, tzitzis) it is still encouraged by the poskim as a way to keep ourselves aware of our separation from goyim. That applies even moreso when going to work; the last thing a jewish man wants is to end up feeling like one of the crowd in an office full of inappropriate relationships, language etc.
Protection: very often, the desire to not make a chilul hashem will prevent a man from doing something he ought not do, because he is noticeably jewish, a representative of hashem.
Status; the rambam says that talmidei chachamim and their students are noticeable in their dress. They look different from the general populace.
Clearly self expression in the form of dress is not a factor in the halachik and hashkafic discussions of gedolei yisroel throughout generations. Largely because for men, it is non existent.