It must be excruciating (or not) for an author to see their work adapted for film. Especially a novel or play or short story that so defined a writing career. You have this creation, elevated to near mythic status, suddenly entrusted to a gaggle of “Hollywood types” who have a very different creative process than yours. And it’s almost entirely out of your hands. Thanks for the rights, here’s your check, now fuck off and let us make our movie.
The end result is often a disaster—the source being too weighty, thematic, or simply imaginative than what Hollywood could pull off. The author might feel betrayed and burned, and wary of letting anyone from Tinseltown touch their work again (unless the check is really big, of course).
But on rare occasion, an adaptation transcends its source—if not entirely, at least in several critical areas that show true vision, and are welcomed as artistic and cinematic achievements. For all its flaws—many stemming from its complicated development process and even more torturous production—Blade Runner is such an achievement.