Why no species fanbois in Star Trek?

A human inmate in "Whom Gods Destroy" wears an Andorian suede tabard. I often wondered if he originally owned the fluffly pink bathrobe worn by the facility's Andorian inmate.

A group of dark-skinned humanoids in ST IV wear Zaranite clothing (from TMP). Meanwhile a humanoid woman in ST IV wears Arcturian clothing (also from TMP). Actually, that reminds me, in "The Conscience of the King" - at least in the script - the play of "Hamlet" is being performed in Arcturian-styled clothing.

An Andorian Fast Food outlet (Shop 01-754) is located on the DS9 Promenade [as seen on the directory board in the television special, The Science of Star Trek].