The best books make terrible RPG settings. The best RPG settings are things that don't make for (IMO) good books, because they are sprawling, unfocused, and not really about anything in particular. As novels, they sometimes work well page by page, but not taken together as a whole, because they almost always drift off into slow moving muddled messes. A metaplot is useful for a novel, or a series of novels where the plot and the metaplot are largely one and the same. It's not useful for an RPG where the plot is created at least in part by the protagonists and not any single author. It's a pretty good bet that if the novel involves saving the universe, that it's a bad setting for an RPG.
A good RPG setting isn't about one particular thing. It is big enough that there are many equally important things going on all over the place. Some or most of them probably aren't related. A setting with a metaplot is almost always a setting where there is only one important story to tell, everyone knows what it is, and your characters aren't in it.
The only way to dodge that problem is to move the time frame and space of the setting to somewhere that the metaplot is rendered irrelevant, which almost always requires massive secondary invention so that the setting is now no longer actually the setting of the book but rather a sprawling, unfocused, setting that no longer has a single metaplot. Arguably the Star Wars RPG is a good example of this sort of secondary creation. The equivalent literary creation would be the Han Solo trilogy set in the same universe as the movies, but having a rather different metaplot. So for example, you could probably write a decent Middle Earth campaign setting, if your setting involved nothing to do with Sauron, the Noldor, the Numenoreans, or the Rings of Power but resolved something unhinted at of similar stature offstage of the main plot. Afterall, Morgoth had many servants... Or you could probably do a decent Hogwarts campaign, that wasn't set in Europe in the 20th century and hense probably wasn't about Hogwarts. Sadly, the average player is sold on a setting by its familiar peices, and secondary invention of the same quality as the original inspiring work is very difficult and rarely done well.
While I don't like metaplot for a setting, you can get away with it if the entire point of a setting is an adventure path. The best example of the use of metaplot in an RPG is the Chronicles of the Dragonlance adventure path. It's also a terrible setting for a RPG that isn't 'Chronicles of the Dragonlance'. But while a good inventive DM can use that AP as the basis of a campaign (and a bad one can use it as a pointless railroad), it's pretty much just a highly extended 'one shot'.
MMORPG's I think make a huge mistake in trying to give their settings big lore building Metaplots particularly ones driven by NPCs. It's impossible to make that convincing because nothing ever changes and everyone is that hero, so in fact no one is. The mistake is driven by the fact that as a society are far better, more experience, and more mature in the art of writing novels than we are in the art of writing RPGs. People keep doing what they know works in other mediums, and failing miserably I think as RPGs. I think much of the appeal of Mass Effect was going to be that it merged successfully the appeal of a novel with the appeal of an RPG, but the third installment failed when it was revealed that that promise was never going to be made good on - something that should have been more obvious from the plot of the second installment than it was.
I'm curious to see if the forthcoming Numernera cRPG manages to avoid this. The original 'Torment', while a very good game, didn't and as a result the ending was one of the few parts of the game I felt really cheated by. Additionally, the original 'Torment' isn't really an RPG as I understand the term, because you can't really create your character (much less change anything by your choices), but rather a traditional Adventure game (similar to Grim Fandango) with an RPG combat engine tacked on to it. Fallout II did a better job IMO of being an actual RPG, but probably the best example of good design for an RPG in a cRPG format was the old Exile titles by SpiderWeb, particularly Exile III. Still, even then you have a single NPC driven metaplot.
