I think with JBJ, it really is that drive to prove he's "still got it". Releasing a greatest hits collection will not prove that to him, won't feed his ego and won't bring him that validation. He'll readily use modern production, outside songwriters, commercial sound - but to create something that proves to him that he and his new releases still resonate with the public. He wants that outside affirmation, which is why the failure of, for example, Everyday probably hurt him quite a bit; if he didn't care about that the track would've been on the GH. But he does care.