Actually what you described is more low fantasy than high fantasy, which is what Morrowind actually is. If there weren't a need and demand for low fantasy we wouldn't have Game of Thrones... plus, how often do you really see magic in LOTR? So making magic a viable but not all encompassing game play mechanic, and emphasizing realistic conflict, is in my opinion, not done often enough. Even if you stripped the magic out of Morrowind, there's more than enough to make it interesting, but the high fantasy elements are what put it over the top into classic high fantasy. However, it's the realistic faction conflicts in Fallout NV that make it irresistible, and that is absolutely doable in OpenMW as it is, although we could improve on it.
And indeed, Fallout 3 and 4 are about as Post Apocalyptic (Gamma World or Fallout) as my left toe. They both seem like they take place a decade immediately after, not after the considerable rebuilding that actual people would do as soon as they reasonable could, which is what we had in FO 1, 2, NV, and Gamma World.
Hence my interest in what I'd like to call "OpenGW" and declare openly a need to also use OpenMW 1.0 to blend a skill and xp based level progression system, where you are rewarded for both solving larger problems (completing missions) and honing/training your skills (Morrowind as it is.) I'd say that's entirely relevant to both the fascinating pagan period role playing you described, lysol, and Greco-Roman roleplay as suggested earlier in this thread.
Also, I'm betting some people reading this might be familiar with the film "Zardoz" and if ever a movie screamed for an RPG based on its setting, that certainly did. If ever a setting called for a protagonist to highlight static vs dynamic culture in the way Morrowind did, it does, and would support the kind of gameplay I'm looking for in OpenGW, or hell, maybe even OpenMW with magic throttled back and better support for guns.