Yeah. I'm one of those people who believes that if you just be yourself, you'll never be anything more than what you are. And that relationships are built on compromise, so Parappa's quest to improve himself for Sunny's sake makes the ship more valid in my opinion, and Sunny is at least implied to have tried doing the same thing in PTR2.
Yeah! That'd be cool. Speaking of Sunny, I could see a campaign for her centering around playing off of Parappa's endless quest to get better by improving herself so he doesn't have to worry so much, and her songs being soul. And exploring the lore a bit (Why should we never use Joe Chin's Chains for our Chainsaws?)