This is why.
The reliance on overused tropes and cliches makes this movie dangerous. It gives the entire genre — print, graphic, film — a bad name. By its very nature, fantasy is most vulnerable to appearing ridiculous. Unlike, say, a contemporary thriller, if a fantasy movie is bad, it's not just a bad movie, it's a stupid idea, a foolish excursion into unreality — escapism at its most puerile.
If you create walking, talking cliche of a movie and market it heavily, the crap splashes on everyone working in the genre. How many people will see a trailer for a dumb-ass, cliche Conan and not bother with HBO's Game of Thrones?
I don't want to even think about the damage it does to Howard's credibility and prestige, so painstakingly built by the very people who work this forum and TC and the venerable REHupa.
It's NOT "just a movie." It's a statement.
Couldn't have said it better myself. How much nonsense did we already have to put up with when the sins of Conan the Barbarian were visited upon Howard? Roger Ebert assumed the fascist sensibilities of the film were perfectly faithful to the author--nothing could be further from the truth. Tons of idiotic authors apply Nordic mysticism erroneously to the Celtophile Howard, not to mention fallacious National Socialist sympathies.
What about this film? Say the film is terrible (astoundingly unlikely as it is). We'll get idiots saying that Milius was right to deviate from Howard, since Lionsgate are touting this as a "faithful adaptation." Therefore, their argument would go, if this was a "faithful adaptation," and CtB was an "unfaithful one," Howard's work was just puerile, shallow pulp in need of "elevation" by an artist such as Milius. We already have fanboys saying that Milius made Conan "better" than Howard: how much more are we going to hear this when they have a supposedly "faithful" film to compare it to?
Then we'll get the added bonus of people attacking REH for stuff he didn't even do. If they don't change Singh's name, people will accuse REH of being racist towards Sikhs and Indians - something he most assuredly wasn't, seeing as Khalar Singh doesn't exist in REH canon. The ludicrous "King becomes powerful, Queen must die" Acheronian garbage will have people accusing REH of misogyny and patriarchal leanings. Having one of Conan's nemeses be black--AGAIN--after Doom and Bombaata gives the impression that the Cimmerian has it in for black people. And, as with Conan the Barbarian, people will accuse REH of falling to the "Home village and parents destroyed by villain, life becomes quest for revenge" trope every other fantasy story is blighted with.
So yeah, it matters.