What is it exactly is this grimdark that people are against?
In my case, that it's incorrect and bad writing to equate a greater level of violence and/or squalor (or, rather, the detailed portrayal thereof) with a greater level of realism. That in itself is an adolescent attitude, in that it is wrong to suggest that the more wretched the situation, the closer it is to representing the truth about how life really is. But that raises the question of whether it is readers making that mistake or writers. After all, this is something that readers talk about, if only because there are far more readers than writers.
I wonder where the problem actually lies, if it lies anywhere. Can writers be blamed for giving the public what they appear to want? And given that the accusations are always made about the same 4 or 5 very successful writers, is the concern less that there's a deluge of horrible torture-porn on the bookshelves than that an awful lot of people want fantasy to be 30%
Lord of the Rings and 70% the London Dungeon?*
Personally, I'd like to see other elements of fantasy challenged beyond this. Such as why stories so often concern the fate of the kingdom/known world, and why they have to be so bloody long. I know this is virtual heresy, but if I could make fantasy writers forget about
Lord of the Rings for just one year, I would, just to see what they'd write instead.
(It's also worth pointing out that older books simply couldn't give detailed portrayals of unpleasant things, but managed to make their point perfectly well. Take the murder of Nancy in
Oliver Twist, for instance. You don't see Nancy's skull being smashed in, but you know damn well that's what's happening, and the fact it's unseen probably makes it all the nastier.)
* An exaggeration.