No tanks in an Ork list... do you REALLY think that'd be easier to paint? Unless it's like... a nob biker list, but that's kinda boring and overdone. And let's not get into no tanks in a Guard list... or in a Sisters list...
... screw it. Tanks make armies EASIER to paint. It's easier to paint a tank than a squad. Easier to paint a transport and a squad than two squads.