Josh31:
Maybe there is a fkaw in your given:
1) Maybe they dress in formal black and white because there is a concept called “b’chol drachecha da’eyhu” and “shivisi hashem l’negdi tamid”. If you were hosting the president, I’m sure you would feel that the occasion warrants the status of black-tie. We are constantly “hosting” Hashem and should dress appropriately.
2) where does it say that another person has to be able to tell if you are dressed for Shabbos? I think it is only that you need to change your clothes, preferably to nicer ones. It is usually pretty clear when someones shoes seem extra spiffy one day a week.
3) So you are saying that the bride and groom deserve more honor than Hashem in who’s Presence we are constantly in?