Those fears are somewhat justified. While great at interpreting and adapting complicated literary works, D&D don't have a great track record with just farting around in other people's loose fiction. And we're not just talking about them unsuccessfully trying to end GOT with nothing more to go on than a few of George R.R. Martin's scribbled cocktail napkins. Weiss was attached to a failed Halo project, and Benioff co-wrote the not-great X-Men Origins: Wolverine and Troy. And if you can't do something exciting with the greatest extended universe ever created (Greek mythology, not Marvel), it's going to be an uphill battle accomplishing anything in a place that has midi-chlorians.