how does a fight prove anything about ideology? How does violence stop violence? You move people through ideas and by appealing to their hearts and minds. Aggression is intimidation. It's getting something by force. I don't want the foundation of the bruce/clark friendship and partnership to be some uneasy alliance where they tolerate each other's existence as some sort of balanced weights on a scale. I'd rather them find common ground and move past their differences in a real way so that they can become comrades.
It sounds like you ultimately get that, which is why you end by saying they would "talk it out." however, if talking is they key, it makes the fight rather meaningless, doesn't it? It also wouldn't explain how they could go from such vicious fighting to just talking when nothing had fundamentally changed between them, and they had supposedly been well aware of each other's ideologies before. They don't need to talk to each other to understand that.
From what i gather, there's a bit of a theme running in the film about isolation as a result of becoming jaded. Both bruce and diana sound like they've either become more aggressive or departed the hero business because they have suffered losses or grown cynical. Superman, by contrast, is connecting with people. He's living and loving. Also, his appearance on the scene might have made diana and bruce more introspective about their roles in the world as heroes. Ultimately, superman not only showing that he hadn't given up hope, he had made connections, he had humanity, but also demonstrating his values and strength by fighting for love and dying to save others, bring about a turning point. It all gets bruce and diana to embrace hope and heroism again, and the world can be assumed to follow. That's powerful, as far as i'm concerned, if it is indeed how the movie goes.
spot on