I prefer such narratives as well, but unless they're really dedicated to shaking things up (which is possible!) I have to agree that the rivalry will probably be in the ground within the first half. I have no opinion on whether or not the main cast being divided philosophically would benefit the story, but I will say there isn't a strong amount of evidence that there's any deeply held philosophical disagreements at all since nobody we know is taking the 'wrong' (ie. conquering Eorzea) side and it seems from initial impressions that Koana is an equally valid claimant who just happened to hire Thancred and Urianger.
