Well, we have to start our definition of "fantasy" somewhere, otherwise we end up going all the way back to the caves and wall paintings about thunder gods.
While I can certainly understand (and agree with, to an extent) arguments to the contrary, right or wrong, Lord of the Rings is effectively the beginning for modern fantasy. If we use that as our seminal event (wow, that's an interesting word in this context), it and the Chronicles of Narnia absolutely do present baseline fantasy worlds with very few shades of gray. They're present (Sarumon, the reluctant heroes who appear in Lord of the Rings, some of the supporting characters in Narnia), but on the whole, the world is sharply divided into Good and Evil.
Obviously, REH's work was popular throughout this period and presents a very different vision of the universe, and is in a lot of ways the thematic forebearer of a lot of today's more "realistic" fantasy fiction. But while Conan might have enjoyed a resurgence of popularity in the 1960s, it was only after the flower children rediscovered Lord of the Rings and made it hugely popular. I loves me some Conan, but it would be tough to say REH's vision of fantasy is more dominant than the JRRT vision once both their works were in wide circulation.
The pendulum swung towards Conan and Fafhrd and the Grey Mouser and ultimately the Black Company and A Song of Ice and Fire in time (I bet it could be argued that Watergate and Vietnam changed the national perspective on pure and noble heroic leaders and absolute villainous opponents), but once the pendulum had swung far enough that direction, we got the reactionary (in the least perjorative sense) fiction that Blue Rose is based on. That is, a world where there is Good and Bad (which is mostly distinct from Evil, which also exists), where heroines (and even heroes) might be flawed, but to a much lesser degree than in the "shades of grey" fiction, and where hope is not a delusion but a vital and essential part of the world, and one where Good ultimately triumphs over Bad (and Evil) and where animals aren't frightening beasts of the wood, but helpers and companions.
I really see this as going full circle (in a new evolution) towards Narnia and Middle Earth, two of the core works of modern fantasy, especially the latter. But plenty of people don't need any more reheated Middle Earth works (I have a pretty strong aversion to most of the wannabe fiction clogging fantasy bookshelves nowadays) -- witness the popularity of The Black Company and A Song of Ice and Fire -- and I don't think, viewed in this light, it should be a surprise that they would dislike "romantic fantasy" which is a modern take on many of the themes that Tolkein and Lewis wrote about. Heck, Narnia even has a talking horse companion!