Op - even if the bride is ok with it now , it might well have not occurred to her that by wearing something bridal, you will end up being the focus of attention, not her. She will spend part of the day saying "oh I don't mind" at all the comments, rather than talking about her own outfit.
It's very rude to set out wearing something that you know will make you the centre of attention at someone else's wedding.
So, why do you think it's ok to wear an outfit that gets all the attention (mainly negative, but still the outfit that will be talked about, probably more than the brides) at someone else's wedding?