Yeah, but the fact that the 4th "doesn't" use Sage Mode in battle doesn't make him any cooler or more believable. I mean, he's the guy who had enough chakra control to "invent" the rasengan. And he is able to use at least some natural energy. So why wouldn't he learn to control it? Why would he give up one of the strongest weapons in the entire series?

I'll tell you why: because he used to be Naruto++, and Kishimoto had to nerf the poor guy.