I am going to admit it. I wore an white suit to my now SIL's wedding (well over 20 years ago now). I had never heard this rule, and that suit was one of the nicest ones I had. For a summer wedding I thought it was perfect-lightweight, pretty, traveled well. I cringe a little looking back, but at the time I had honestly never, ever heard this rule.
My SIL and my PILs were gracious and never brought it up even once, though I am sure they noticed. I have my issues with my PILs, and often make fun of their nearly hysterical hospitality (DH's wording for their over the top need to get you something, anything, every time you sit down). But they were certainly gracious about my faux pas.
I think it is a silly rule. Noone was going to mistake my business suit for a wedding gown. That being said, there are plenty of rules that I think are silly that I nonetheless follow in order to get along with folks. These days, I would never wear that outfit to a wedding.
Back to the OP:
A surprising number of the women on both sides want to wear white or ivory skirts or tops. I thought it was a pretty well-known "rule" of weddings and receptions that nobody but the bride wears any kind of "bridal" color, but evidently that's not the case? Can anyone confirm that for me?
My understanding (now) of the rule is that you should not wear a white/ivory outfit, but a white/ivory blouse or sweater would certainly be within the realm of okay and a white/ivory skirt would quite possibly be okay, depending on what it was paired with and the style of the skirt.
It's making things a bit awkward...I was able to steer people away from white on the basis that my dress is ivory, and I was afraid it'd look dingy next to a true white. But now some family members are coming back with ivory options. I'd like to find a way to communicate that I want ivory as a me-and-groom-only color (his tie will be ivory, with a different colored shirt) without sounding like a controlling bridezilla, especially to the future in-laws I don't know quite as well. Anyone have a gracious suggestion for how to do that?
I think others have had better suggestions than I would come up with on this though I do think it is a bit much to expect that noone includes a white/ivory piece in their ensemble for the day. Since they are asking, I don't think it is out of line or bridezillaish to state a preference.
But I do think you are stretching the rule to presume that noone will have white/ivory as a component of their outfit. Many men will almost certainly be wearing white shirts with their suits, at a minimum. And you might even get some poor soul, like I was back then, who isn't aware and wears a white outfit.