Perhaps some of those so-called "bigots" are young girls who really shouldn't have and don't want a penis exposed to them? Clearly women and girls are the ones who should be deciding who they share a changing room with (generally not a person with male genitals) .
It's a woman's changing room, not a whoever-you-like-seeing changing room. There is no reason (other than some sort of puritanism) to get freaked out about girls seeing penises. In this context, it's just a body part.
The idea that only uncivilized societies allow for public nudity is an ignorant and self-perpetuating colonialist stereotype.
Not wanting eg your wife to see a penis, especially a feminine woman's penis, is laughably insecure at best, and bigoted and hateful at worst.
Similarly, not wanting your assumed daughter to see a penis is harmful to her (or potentially his) emotional growth, and should be considered borderline child abuse.
You are putting many words into my mouth - for starters I didn't mention anything about uncivilized societies. Second, you don't get to decide what a women does and doesn't want to see - especially if you're a man. As it turns out many women and girls would be uncomfortable around male genitalia when in a changing room for women. I suppose you would be OK sending a girl "d*k pics"? What would your excuse be? "Don't be so insecure!!!"
fully valid women who were born with penises are 1000x underrepresented in your completely arbitrary 'women' group, therefore should get 1000x weighting to their opinion