Well, when Smith had him saying those things, he was using Miller's Dark Knight Returns, as the Joker was catatonic during the years Batman was gone. It's when Bruce has taken up the mantle, again, that the Joker recovers. That's where Batman was shifted into being the Joker's main motivation. In pre-DKR comics, he'd just been doing crime for the sake of it, though he enjoyed his confrontations with the Bat.