Yes, even faster selling than Harry Potter books or Dan Brown stuff.
The thing is, if married women with kids would like a bit of rough in their bedrooms or at least in their fantasies - that's fine. And, I'm guessing that a lot of the women who are really into this book have never been exposed to BDSM erotica before.
And, I think erotica is a good thing and if this book is what it takes to get the types of mostly married, mostly republican, mostly with kids, women who are buying this into BDSM erotica then, you know, you have to start somewhere.
But, now that you've read Playskool's Mommy's First Bondage Porn, let me suggest some stuff that will really knock your socks off.
1. Justine (In some editions this book is called "The Misfortunes Of Virtue") by Donatien Alphonse François de Sade. Not only will you get a hot BDSM orgies involving the young woman and monks, you'll also get a much more liner and believable plot with more developed characters than you are used to.
2. Sleeping Beauty by Anne Rice. This is actually part of a trilogy but the second two books just cover the same ground and in less interesting ways. In this book you'll even find a few male subs, if you want fantasy fodder for when you are on top and not just the bottom. Variety is the spice of life.
3. In the Cut by Susanna Moore. BDSM plus serial killers plus linguistic theory. Yummy.
4. The Story of O by Pauline Réage. Everyone's heard of this book but most people haven't read it because the film version sucked. The book, on the other hand, is an awesome exploration of domination and submission.
5. Lace 1 and Lace 2 by Shirley Conran. Don't let the stupid made for TV versions deter you. These two books are pretty much a collection of every type of heterosexual porn possible, from BDSM to golden showers, to harems to voyeurism/exhibitionism to whatever. It's all in there - including a woman masturbating with a live goldfish.
6. Come Closer by Sara Gran. A story of a somewhat repressed woman who gets possessed by a demon and the demon gets her to do exactly what you'd expect in a dirty novel.