How many "sexy" books can we read?

One thing I've noticed through my blogging/FB/Twitter, blah, blah, blah, is the abundance of books that have "sexy" as part of their description. By "sexy" I believe the blurb is saying that there is a good deal of overt sexual activity that takes place in the book. The question of whether the sex is an integral and necessary part of the plot probably isn't important; it's the fact that it's there, and probably in abundance, that is important. The assumption is that sex sells, that readers want a good dose of sex with their books.

I wonder if this "sexy" aspect is important as a marketing ploy.

Do you write sex into your novels just because it adds to the book, maybe even making an ordinary or so-so book more attractive? Do you include it just because you feel it's a requisite of books today?

I think many of us writers do believe it's needed, and we add it for the extra oomph we feel it gives our books.

What do you think?