I just thought Diana and Clark being together made sense because Clark will outlive Lois eventually just like how Diana will outlive Steve and Bruce. The two of them being immortal and of similar strength means superman doesn't have to worry about hurting her accidentally do to his godlike abilities, and wouldn't constantly need to have control over his powers. 

Also Batman in the comics is far more paranoid and doesn't let relationships get to him very much when compared to the justice league cartoons.

So when written properly I think Diana and Clark makes more sense.