I'm guessing that since he adulated Sparda, he would've tried to follow in his footsteps, sort of. I see him killing Mundus, and ruling over the demon world in his stead. I sure as hell don't see him attending a meeting to elect a new demon ruler

Imagine Beowulf sitting at a small round table XD
He never really seemed to care about humans, so he might want to close off the entrance to the human world. But then, we don't know much about him, do we? Maybe he wanted that power to protect something: ''without strength, you cannot protect anything. Let alone yourself.'' (Vergil to Dante in DMC3). I first understood this as him wanting more power because he failed to protect his mother from the demons. If he wants to protect the demon world, ''our father's home'', then he would need that power. Then again, he could also have meant protecting his legacy, i.e. his child or his wife and child. But there's no evidence in the games that he actually had a child. Besides, he would've had Nero when he was eleven or so.
I suppose he may have been thinking about having a family, in order to continue the Sparda bloodline. Seems like an honorable thing to do. Selfish but honorable. He died before he got the chance to have one.