I think a more visually detailed NOVA is kind of necessary when you have such a large, plant sized model. The problem isn't that he's more "realistic", the issue is that the details are half hazardly tacked onto his body without much care or intention. Its just grime, dirt, and sporadically placed metal patterns with very little cohesion.
It's a shame, because, otherwise, Air Riders visually looks fucking great. The art style is genuinely pleasing to look at. And not in a "let's pump the game with four gorrillan shaders and graphic effects" kind of way.