I like these types of scenes also. It's not a new thing; there is the oft-used trope of Superman feeling like he's living in a world made from cardboard, and it's only when he goes up against a powerful enough opponent - in a location where there's no chance of collateral damage - that he can really, really cut loose. I think one of the animated series had scenes like this with him facing off against Darkseid.
I also like the idea that Superman operates at a certain power level (an insanely high one, admittedly) most of the time. But in some scenarios, just through sheer willpower and exertion, he can push beyond his mental and physical limits and go even higher. Humans can do it in sports events and marathons and high stress situations, so it makes sense that a Kryptonian could too. He did this at the end of the Superman 1978 movie when he was emotionally wrecked by Lois' death and flew round the earth faster than light and he's done it since in many other medium also. Lifting an entire island full of Kryponite in Superman Returns whilst injured is another good example, and we could see the impact that had on him. It's not something he should be able to sustain for a long periods, but I'm all for the idea of him not really having many limits at all when he pushes himself 1000%.