I was directed to this essay yesterday, entitled 'The Bankrupt Nihilism of Our Fallen Fantasists', in which the state of 'nihilistic' modern fantasy is bemoaned and a call for a return to the non-profanity-strewn 'heroic' and 'mythic' fantasies of the past is made. I think the author is conflating two separate issues here, the nihilistic/gritty/realistic 'New Fantasy' of the last two decades or so (a sweeping generalisation), which isn't really that new, and the proliferation of overt sex/violence/swearing in recent fantasy books.
Dealing with the first issue, it's an odd point to make. The problem is that the author bemusingly names J.R.R. Tolkien and Robert E. Howard as his preferred flavours of fantasy. Which makes very little sense, as few fantasy authors are more nihilistic than Tolkien and Howard.
In Tolkien, Middle-earth and the world of Arda are in a state of perpetual Fall, from the very moment it is sung into existence when Melkor/Morgoth starts trying to cast it into darkness. The Silmarillion is a nihilistic work: almost every character of note is slaughtered in its pages, armies of balrogs and orcs obliterate everything that is good and heroic in Beleriand, good men are corrupted and slain and victory comes only through a desperate gambit at the very end. Even that has its consequences: Beleriand is destroyed, hundreds of thousands of people are drowned and it is made clear that Morgoth's defeat is only temporary, as he is prophesied to return and his lieutenant, Sauron, remains behind to continue causing problems.
The Lord of the Rings is much-reduced or thinned re-enactment of this tale on a far smaller, less impressive scale, but even on its own terms is an inherently melancholy work: Middle-earth is saved and Sauron destroyed, but at the cost of more blood. Frodo is corrupted by the Ring and fails in his quest, and victory only comes through the unwitting intervention of Gollum (though the point is made that it was a single act of charity, Bilbo's decision to spare Gollum in The Hobbit, that ultimately saved the day). Boromir is corrupted by the Ring, though he has a redemptive moment. Frodo is emotionally wrecked by events and cannot enjoy the fruits of his struggle: eventually he must leave his home behind forever. Even the victory comes at the cost of myth itself: the elves depart Middle-earth, the hobbits are absorbed into the race of man, and magic vanishes from the world. After the events of Rings, the world becomes mundane and less heroic (in fact, it becomes our world). Tolkien even foresaw that after the events of Rings Gondor would become a divided nation of petty politics, and abandoned work on a projected sequel, The New Shadow, because he felt it undercut the victory of Rings.
Of course, there is heroism in Lord of the Rings, moments of triumph and light, and Middle-earth is saved from destruction or dominion. But it's not a happy ending, and Tolkien makes it clear that whilst the world survives, it is also much less than what it was before. The Silmarillion is even bleaker, with very few characters (perhaps only Tuor and Earendil) surviving unscathed or not having committed heinous acts of violence or, in one case, incest.
As for Howard, his worldview was inherently nihilistic: the natural state of the world is barbarism and anarchy, with civilisation only a passing fad which will soon destroy itself and restore things to the natural order. Conan gets involved in most of his adventures out of a desire for varying combinations of riches, sex or violence. He has his moments of true heroism, but the impression Howard gives is that Conan is an inherently violent character who cannot abide defeat and who is primarily motivated by his own desires. Conan is capable of heroism but his motives are rarely pure.
Of course, one brief look at the mythic inspirations for Howard and Tolkien, the great Norse sagas, the Arthur legends, Greek myths and so on, reveal stories far more tragic, blood-drenched and horrific than anything the likes of Abercrombie or Martin has ever come up with. This notion of pure black vs. white heroism ever being a dominant force in either mythology or fantasy literature seems to be illusory.
The other point, about fantasy being overloaded by graphic imagery and swearing, is better-taken. Sometimes the feeling in modern fantasy is that 'adult' has translated as 'shagging, crapping and disemboweling' in all their glory, which after a while can be tiresome. Brandon Sanderson has shown it's possible to write entertaining and somewhat original secondary world fantasy without resorting to these steps, whilst Patrick Rothfuss pushes the less-savoury aspects of his world (there is an intimation that Kvothe suffered sexual abuse whilst living rough on the streets of a city, but it isn't pushed into the reader's face) into the background.
But at the same time being able to address such issues freely is useful. I certainly don't doubt that Howard would have employed them if he hadn't been restricted by the publishing mores of the time, whilst Tolkien certainly wouldn't have, though he didn't skimp away from darker elements where necessary (particularly in his darkest story, that of of Turin). Amongst modern authors many still have their heroes, but are less interested in displaying them as unmotivated do-gooders. In A Song of Ice and Fire the single most heroic moment in the series is probably when a character jumps into a pit to fight a bear one-handed. The character doing that is someone who was previously presented as a heinous villain, but as we get into his story we learn that his motivations are understandable and he is the hero of his own story, though as events progress Martin doesn't let us or the character forget the darker things he has done. Outside of that, we have characters like Jon Snow who are more obviously heroic (though I suspect that his story will get more complex in the future).
It is interesting that the article roundly dismisses The Wheel of Time, a work that is more closely following in the tradition of Tolkien with more overt 'good guys' and 'bad guys'. Heroism, people putting their lives at risk to save people who frequently hate them (Perrin saving a Whitecloak army which has sworn to kill him), is found there in plenty.
The problem with the essay is that its author has fundamentally misread Tolkien and Howard. The age he bemoans the passing of, that of heroic and mythic fantasy entirely lacking in moral complexity or darker elements, has never existed in the form that is set out.