The controversy stems from someone becoming offended with what they read. That's why it's so popular right now. Everyone wants to get in on the action. The books don't have to be well written if it captures the attention of someone who is willing to make some noise about it. Twilight is a prime example of that. The Twilight books were ok at best...as are the 50 Shades books...but the media hype is what makes them succesful.
I completely agree with you, in terms of that the only reason that it is a popular series in the mainstream media is because somebody has created noise about it because they were either offended or found the material to be too risky for their liking. I did delve into the first book for a few chapters, and found that the characters were engaging to the point of their conversation was interesting, but other than that, the characters, in my mind, really have no depth at all and are a typecast of a formulaic structure. Furthermore, the series is not well written and reads like a mere fantasy dream (like
Twilight does). The difference I am finding between this series and the
Twilight series is at least the
Twilight series brought in some myths about vampires, at least it had a fantastical element about it that offered a different world to the readers. Not that
50 Shades of Grey doesn't offer this, but it offers it in a sexual format, which to mainstream media provides a major outlet for controversial dialogue.
I truly believe that if it weren't for the media hype about this series, it would be just another erotica on the shelves that may or may not sell to a select group of readers. Now there is nothing wrong with reading books that have BDSM in them, or erotica for that matter, but it is only due to the subject matter that has made it into the limelight and even then I am still baffled as to why... considering the amount of books you could find with almost the exact same content

. That's what happens when someone makes noise, either the book is shamed and painted in a negative light, or it is embraced. Lucky for the author, they've made some money off of it, and even a movie deal... that's pretty amazing considering that the writing quality is not even close to what I would call good literature.
It's fluff, pure and simple; something people do like occasion.