There have also been increases in those who identify as LGBT[2]. Such massive increases in younger generations can't be explained away by cultural changes IMO. I don't think it's a coincidence that at the same time that exposure to hormonal disruptors has increased, changes in gender and drops in testosterone have been found.
[1] https://www.healio.com/endocrinology/hormone-therapy/news/pr...
[2] http://news.gallup.com/poll/201731/lgbt-identification-rises...
https://en.wikipedia.org/wiki/Diethylstilbestrol [See Des Sons]
I remember reading about how the increase in mental illness could just be that we are better at diagnosing and recognizing them (and lazy doctors who would rather just prescribe something for your "depression").
A) I don't think we would see a massive number of older people coming out of the closet, because this culture change is generational. Most of your peers aren't going to change their minds just because a younger generation is more tolerant. It's the same reason my 100 year old (really!) grandmother may still use the occasional racial slur. I definitely think there's more peer friction for an older LBGT individual than a younger one.
B) I don't think these numbers are actually out of line with the impact of cultural change.
C) Base on your linked datas, religion may also be a factor. Given that religion is on the decline in the US, especially among millennials, I wouldn't rule that out as a factor either.
It's probably a combination of factors as usual, and maybe endocrine disruptors is one of them.