Well indeed. There are, alas, one or two stupid people in the world who
would stick their hand in the fire if you told them to do so
I can also think of a couple of well known religious texts which some stupid people have taken as carte blanche to do some very cruel things. Just because that particular prophet didn't consider that somewhere down the line an idiot might be inspired to pick up a Kalashnikov doesn't mean he shouldn't have said that his religion was
really cool, in his opinion
Same goes for fantasy. If someone is such a clown that they think wearing a replica One Ring really will make them invisible then it's not really the writer's fault. Obviously there are limits, such as it would have been unwise of JK Rowling to fill the Harry Potter books with examples of Draco Malfoy dealing crack behind the broomstick sheds, but mostly, the writer isn't to blame for the fools who (mis)read his books.
In the case of Tolkien's depictions of war, in my opinion, it's about the Aesthetic he chooses.