I strongly believe that as long as any sexual act is done safely, sanely, and with consent of all parties, it's your own business and it's not a problem. An individual's personal fantasies and what they do behind closed doors does not necessarily affect the rest of their life. You certainly do get some kinksters who, for example, want to take the master/slave dynamic into their regular life, but even that's only as problematic as you make it.
Frankly, I'm also someone believes that if a woman or man truly wants to be a stay-at-home parent without a career, they should as long as they are doing it because they want to and not due to pressure or coercion (because feminism to me means having all those options). (I personally believe everyone
should have a career, and in a perfect world nobody would choose to do this, but that's me.) That said, you
will get controlling, abusive a-holes who force their spouse to stay at home, and that, to me, is when it becomes unacceptable.
In the same vein, you also get a-holes who enter BDSM communities with no actual idea of what BDSM is and how it differs from abuse (like the author of
Fifty Shades of Grey), or people who do know that difference, but use BDSM as an excuse to find victims to abuse.
These are the types of people who will coerce, who will push boundaries, who will hurt their partners without realizing or caring. These are people who should not be in the community.
That is not, however, to say that there isn't a swath of people who just enjoy the different elements of BDSM, be it the helplessness of being tied up or the power of spanking someone. If you want hot wax dripped on your belly and someone enjoys dripping hot wax on other people, let them be happy together. Fantasy is fantasy, and as long as you keep your fantasies separate from your daily life and the important decisions you make, what you do behind closed doors shouldn't matter.
I also feel that your posts don't really take the desires of a number of people into account. For example, in cases of same-sex individuals performing BDSM scenes, there generally isn't the gender dynamic you're referring to. Men from a variety of social classes enjoy being dominated, and part of why it appeals to so many people (women included) is the loss of power or control. You get rich CEOs and politicians who just want to let go for a few hours, and there
is something liberating about that. But just as you get men who are only subservient in the bedroom, so too do you get women who are only subservient in the bedroom. Sexual role-play allows you to try out different scenarios and different roles and discarding them afterwards, be it a sexy nurse and patient or a slave and master.
Do rape fantasies contribute to rape culture? I'm not sure, but I do believe that a s long as they remain in the bedroom between two consenting adults, it doesn't have to be problematic. It may be a symptom, but to say it actively contributes might be pushing it.
Is there a lot of violence in porn? Absolutely, but I'd rather people get it out of their system through pornography than by actually going out and hurting people. For instance, there is a correlation between access to pornography and lower rape rates, as seen in
this study.