A Jew must be recognizable for Kiddush Hashem to occur, it is the recognition linked with the action which creates the KH. Yes, it is posssible wearing a kippa could also do this, but not as obviously as black suit and hat. Why quibble?
I am saddened to read that you think a Jew dressed in a black suit and hat “in the Bronx Zoo when its 90 degrees out looks ridiculous”.