On the whole I think society produces far too much sexual material, be it in fashion, TV, film or literature. To a large extent the sex we are shown on a daily basis especially in film or TV bores me as while it may help change the ratings it seldom adds anything to the story. In academia for quite sometime, I think, there has been a push to actively look for sexual meanings in places where to my mind there is none or it is unimportant to what the piece may be about(More on that subject when I write up what happened at Continuum 6).
This is also big in feminist circles. Many Fems - to my mind - find sex where there is none as part of their ongoing battle with the patriarchy.
Then there is sex in books. My problem here is partially the same as in film and TV. So much is completely unnecessary, but I think there are other deeper problems than that. There are two main rationales and they can be sumarised most simply as laziness and shock.
If you discount modern literature, which mostly to me seems to be about pandering to the accademics I mentioned above by finding sexual conotations in pretty much everything and using that to basically make their characters lives hell, most sex in fantasy is either used to show characters have fallen in love, to confront the reader with how evil the villains are by having them rape the female lead, or both(which is really disturbing)
Funnily enough, the worst offenders(at least in the F/SF I have read) tend to be women. Perhaps for men this is still a taboo area where they need to tread lightly. Many female authors though seem to think any excuse is a good one and while this simply may be another result of poor writing skills,this is an area where I feel more care should be taken by writers, editors and publishers.
The lazy writer doesn't want to go to the effort of properly exploring the gowth of love between two people and resorts to dumping them in bed as a quick and easy alternative. Here lust = love(but to be fair this message in lots of other places too. I don't like it there either). A recent read of mine 'Gladiatrix' had the heroine show her love for the slave she rescues by suddenly making a contraction of his name(which while later explained was wildly inappropriate) and later having them forced(?) into a simulated sex routine where they could recognise each others passion. Depsite this the heroine almost till the very end claims their relationship to be largely platonic. We are supposed to realise she is lying purely on these two clues.
In reality the shock value sex is laziness too. I imagine the author thinking "How can I traumatise my female character and show her helplessness? Ah ha! I will have her raped.". The most recent example of this was in the first Crown of Stars book. The female lead is taken as a slave by a male and he forces her to have sex. Now it is well written and effective and leads into later events well, but is it necessary? To my mind it isn't.
If you tell me that this makes the story more gritty and real, let me point out to you the genre I am talking about. FANTASY! If I want gritty and real I will find it elsewhere, I don't need it in books I read for entertainment, and if you find rape and abuse entertaining, I have the number of a good therapist.