GRRM is a lazy bastard.
BUT, his fiction is not "less than" because it's fantasy, or suddenly popular. All fiction is a "fantasy" of the writer.
Additionally, GRRM is hardly the first writer to stubbornly insist on an antiquated writing instrument. Nor the first to be moody and lazy.
Personally, I both hate his sloth and love his works so far. I read every book (that had been released) before the HBO series and I told people then that it was my favorite fiction I had ever read. For me, it still is.