I'm not an expert in D&D per se, but looking at my shelf I have bought and read a ton of different P&P systems. So I can't say you're right or wrong about the

I'm not an expert in D&D per se, but looking at my shelf I have bought and read a ton of different P&P systems. So I can't say you're right or wrong about the money grab, but I think you're missing the point that some people like world building (maybe more than the stories) and some people like storytelling (and couldn't care less for the world). Some quick examples, a lot of the World of Darkness systems like Vampire, Hunter, Werewolf: You don't need to describe the world like in D&D because it's Earth, with a few differences. All background material is mostly social, political, some tech and "made up" stuff. Contrast this to D&D where you can sell books for every region: the geography, the lifeforms, the history, etc.pp And I think you can't simply say one is better than the other. Some people want to play in a completely made up world and some people like the setting of Earth (with or without extras, there are also systems who don't have any magic or monsters). And this is a huge part of how many source material there is.