Does a good book need sex?

I have been looking around for a good book to read for a while now. I have a study break over the summer and since I heard the advice "If you're not writing, you should be reading", I thought I should to fit in a few books. I'm currently reading Mansfield Park by Jane Austen and I think something more modern would be a nice change afterwards.

So I looked through forums and reviews to find something good. One thing seems to stand out about all of the popular books that other ladies are reading at the moment: everyone is raving about the magnificent sex scenes in them. Never a big fan of this kind of writing anyway, I was under the perhaps naive impression that this sort of thing was hidden under a pillow and never really spoken of. But I suppose I've always seen anything to do with sex as a private matter, something to be discussed only with one's partner, closest friends and perhaps a health professional. Perhaps this is still mostly correct. After all, the only place I've seen women openly talking about this are in online forums, where everyone is more or less anonymous anyway. What is apparent is the appeal of books that contain plenty of very adult romantic scenes. 

Some of my most recent reading was the Twilight Saga. Yes, I know many will immediately picture me as an emo teenager, going weak at the knees over Robert Pattinson. I don't wish to stick on this point for long so to briefly state my own opinion, I own the films and enjoy them but they are vastly overrated and the books are much better, although I generally think that of any film adaptation of a good book. The books were recommended to me by so many people that I eventually decided that I must try them. I liked the fantasy aspect of the story but what really made me like the books was the lack of sex. I have started far too many books that within a few pages have a wedged in sex scene that, I think, adds very little to the story. In the Twilight Saga, there are many romantic scenes and sex is talked about but there are no intimate details and it feels very much relevant to the story.

Having just started writing a novel which will have romantic aspects to it, I'm starting to wonder if anyone's going to bother reading it if I don't include some sex scenes. But should I give up my own principles just to gain a decent readership? Another piece of advice I've heard: "Write what you would read". Well, I just don't read books with explicit sex in them. Call me old fashioned, I probably am, but I think romance and, not just in books, should be about more than that.