Well, the books were written by a married woman who had to do research on BDSM before writing books about it, having no experience in the lifestyle herself. That might say something about why the characters, their choices, their backgrounds, their activities, their personalities, etc. are unrealistic. Plus, it's just a book, so who cares if it's unrealistic? It's a fantasy, that's all it is, and a good one.
Before I read the books, I was thinking, "This must be one hell of a nasty story if seemingly every girl is reading it." Once I read them, I thought, "All these girls hyping it up, saying how much sex is in it and being shocked about it, must be pretty sheltered sexually." And I still think that. Nothing in that book surprised me, and it actually didn't turn me on as much as it evidently turned thousands of other women on. Sure, it was hot and nice to fantasize about and was a great escape from reality, but... it's not as... crazy as it's hyped up to be.
Hmm... maybe I should write a romance/erotic novel trilogy and see how the world reacts.