The web has a ton of fantasy artists. This type of graphic works are often found in games, magazines, comic books, book covers, and even in a few movies. However, this art work has never been elevated into the gallery and museum art scene. Illustration has been added to the canon of art. Norman Rockwell's is good examples of an Illustrator having important museum exhibitions. Pop art, led by Lichtenstein and Warhol, has elevated the images from comic books. Anime artist Takashi Murakami has written Superflat, a manifesto of why anime art is valid in the museum setting.
There are a few reasons I think that fantasy art has not reached being hooked into the art scene. 1. As in some of the examples above, there is not a leader or leaders to usher in this art. 2. Could be that critics have not latched onto a particular Illustrator/artist. 3. What would the movement say? This question is not well defined. 4. Or no artist has taken the work to the right amount of extremes to brake into the scene. After all, Murakami's work is extremely over the top and ambitious. Lichtenstein was making the his work in the moment went the debate of high and low art was at its fever pitch. And Rockwell had the benefit of Post-Modern critics understanding his work in a new light from the Modernist critics.
I think the ground work has been laid for this work to reach the museums and galleries, but something is missing. I laid out some possibilities, but it could be a number of other things as well.