It seems to me that there are a variety of way in which to use 'history' in fantasy RPG settings. While the degree to which an RPG setting uses 'historical elements' is related to the level of magic in the setting, that's not all that there is, I'd suggest there are five levels of 'historical-ness' in fantasy RPG settings:
1) Little to No Historical Elements: I haven't played any of this kind, but a setting such as Eberron or Planescape probably counts as belonging to this category. In those settings, the level of magic renders the world quite alien from any particular historical analogues, but I'm sure one could imagine a low-magic fantasy RPG setting that is similarly devoid of historical elements.
2) Loosely Inspired By History: Here, I'm thinking of setting such as the Forgotten Realms or Mystara. The historical analogues are fairly clear, which enables the players and GM to collectively imagine the game world. However, the level of magic (and the bricolage of historical-like elements) means that while the setting might superficially appears to be (say) 'medieval', the way in which the world works is actually quite different.
3) Strong Analogies To Historical Elements: In this category I would put settings such as the WFRP1e Old World and Dragon Warriors' 'Legend'. In both these cases the game world isn't Europe, but it isn't too far off. It is probably not a coincidence that both settings are pretty low-magic, which means that the close cleaving to the social and political structures of the historical inspirations are not implausible. These settings allow the players and GM to use their rough knowledge of a historical era while placing few demands to 'get things right'. Of course, it needn't always be not-quite-Europe - Kevin Crawford's Spears of the Dawn is not-quite-Africa, for example.
4) 'Real World' With Overt Fantasy Elements: Here we get things like RPGPundit's Dark Albion of Cakebread and Walton's Clockwork and Chivalry. In these settings, the fantastical and magical is certainly part of the world, but many of the historical elements are drawn straight from history.
5) 'Real World' With Subtle Fantasy Elements: While the level to which the fantastical intrudes depends on the GM and the play-style of the table, settings such as Mythic Iceland and Mythic Britain, or TSR's Historical Reference series for AD&D2e are built almost entirely (as closely as is gameable) from 'historical elements'.
What sort of levels of historical-ness do you enjoy playing? And running?
