Carefull ellipses on your sentence have been added here...

"how did it come about that a guy [...] is maybe more popular now that a couple of his books have been [...] adapted into movies [...]?"

Loose adaptations are still adaptations, and as long as his name is on it, at some point.. it will boost his sales. In the same way that I, Robot will help Asimov sell more, without mattering how closely it hews to the original story.

--G.R.R.