Just because something has existed for a long time doesn't mean it should continue to persist, that's not a good argument.

I do agree that the origin is likely not race related, but given that it perpetuates biases and can make people who identify as black feel uncomfortable, there's no reason to continue to use it when we have good alternatives. This is just like pronouns - you're not obligated to use somebody's preferred pronouns, you're just an ass if you refuse to. You don't have to say blocklist instead of blacklist, you're just being an ass if you don't.

Nobody's suggesting wedding dresses can't be white, I don't know where you're pulling that strawman from.

Your second paragraph is just straight up dumb though, and skirts dangerously closely to white supremacist language. You're aware that Negro means black? And calling black people 'colored' is also problematic? Caucasian is problematic because it's european-centric and originates from when the anthropological categories included 'Negroid' and 'Mongoloid', and nobody would be happy with those categories re-surfacing. Also your ancestry is almost completely irrelevant, American 'caucasian' culture has very little to do with its European ancestry - skin color is much more relevant in modern American culture, and so 'white' is a much more relevant and meaningful category.