The boundaries of what's permissible on a television show, at various time slots, has always been a moving target. We can all think of past TV shows that "pushed the envelope" of what was acceptable -- nudity, violence, awful-but-realistic situations -- and which of those things have "stuck" and which haven't. I remember a time when you never saw somebody get hit by a car on-screen. Now it happens all the time. I remember when car crash perspectives first shifted to inside the car, seeing that oncoming car over a character's shoulder -- it was brutal, the first few times. I still wince.
On the other hand, most TV shows have contented themselves with Strategically Placed Sheets in bedroom scenes, or the polite fiction that everyone's wearing underwear after a romantic evening. There have been various pushes toward more nudity, but it seems to me they've slowed down.
Books have far more flexible boundaries. There wasn't anything envelope-pushing about the content of 50 Shades of Grey. The unusual aspect was that a niche genre sold so well in the general market. Readers pushed their own envelopes, in reading it.
I don't think it's the writer's job to challenge their readers -- writers have limited control over who their readers are, after all. It's the writer's job to push her/his own envelope and reveal the depths of her feelings about the subject at hand.
Must you? No, of course not; it's your story, write what you want.
But I believe, and I even have a little data to back it up, that when you do challenge yourself to write about something you feel strongly about, it shines through the page. And readers respond to it. Passion -- strong emotions, no sexual connotations -- is powerful stuff.
Caution: you may not get a positive response. That will hurt.
To provide an example, consider the gay sex scene I posted on Monday (over at Shadow of the Unicorn). I was anxious about that partly because it was a subject I'd never written before, and as a woman I can't fully know what m/m sex is like. But mainly, I was anxious about posting that because all of the emotional content of that scene... came directly from personal experience. So did a fair amount of the physical mechanics.
Everyone has strong feelings about sex, and I'm no exception. I can directly compare that scene -- which people have said kind things about -- to other sex scenes I've written without that emotional connection. Critiquers latched right on to the lack of emotion, in that case. It startled me that it was so obvious. (Posted here for comparison.)
What scenes in your story tapped into your passions? Did it push you outside your comfort zone to reveal such personal things, even in the disguise of fiction?