As a fan, I have read quite a bit about the Zork lore. There’s some seriously interesting ideas there. But in particular, I have a soft spot for Zork Nemesis. It’s the one game that really doesn’t have much (if anything) to do with the rest of the series, you can see it was rebranded at the last moment, but it still managed to be a pretty good adventure.
Normally, these name changes tend to bring with them their own kind of trouble. DMC2 is one easy example. Blood Omen 2 was also not in line with the rest of the saga. But with Zork Nemesis, they at least managed to put out such a good game that it didn’t really matter. Especially considering the previous entry. You could make a case for Grand Inquisitor, but to be fair, I felt that game was excessively comical by Zork standards.
Nemesis looks positively ancient by today’s standards. But then, I think it was one of the first adventure games to actually allow you to rotate the camera (I might be wrong there, but I really can’t think of any examples before it). So it also has some historical value. And let’s be honest, would you really rather play Return to Zork just because it’s more Zork-like?