First of all I just want to say that I am not affiliated with the Superman movie, Warner Brothers or in any way associated with the film. This is all my pure speculation, and educated guessing.
I “think” I have an idea of what the vision is for Superman. People are misunderstanding Zack Snyder’s explanation of what “realistic” means, so I will try to clear things up.
Now, let’s talk about the cool part about being more realistic. Superman’s abilities make him very powerful but also very smart. A being that can move as fast as he does must be able to think faster as well. So Superman is much smarter than he is ever been given credit for on screen. Next, since the audience is getting smarter I think they can handle knowing more about how his powers work and that will open up some interesting avenues of vulnerability. For instance how he gets his great strength and speed and of course how he fly’s. A sophisticated enemy could use this knowledge against him without always resorting to Kryptonite. Of course he would overcome attempts to interrupt his abilities with his formidable and quite intact intellect. Also when fighting a Super-powered enemy; Superman, being a smart and compassionate Alien would at least make an attempt to lead the fight out of the city. I never get why the “entire” fight always occurs within the city. Sure it looks cool, but Superman would know that this puts him at a disadvantage. Even if he isn’t entirely successful he would at least attempt to move the fight out to a more secluded place where he could really cut loose with his powers. For instance he could use his heat vision with suggest intensity that it would be like a Nuclear bomb.
Next, realistic doesn't mean that Superman can't pick up a car or use his Superpowers; it means that he can't pick a car up from the bumper. The bumper will break first. It means that no matter how strong he is, the weakest link will always break first, so when Superman wants to save the day he has to be careful. If he wants to pick the car up and not damage it, he has to do it from an angle that works. He can't fly in at 300mph and move someone out of the way of a bullet or other peril because if you fly into someone at 300mph it will kill them. So instead he would need to huddle over them or stop the materials from falling on them, that sort of thing.
Also, he could not run Superfast into the middle of the Daily Planet or leave the Daily Planet at super speed without causing a huge air displacement that would be like 50kt winds (enough that everyone would notice). You can't do that 10 times a day everyday without someone noticing. So the real "Physics" have to be considered. It doesn't mean that he can't run superfast or fly superfast or be super strong. He just has to be more careful, where, when, and how he does it. And that is pretty cool. Remember, he lives in a world made of "cardboard" he is always constantly considering how to maneuver in a very brittle world.
Lastly and briefly, don’t forget about the realistic side of the mental state of a being with the Powers of Superman. How much does he enjoy it and struggle with the powers and responsibility respectively. How often does he think about how easy it would be to stop all the Wars and just take over the whole thing? Even though he is the Boy Scout and is incorruptible he must still occasionally struggle with the brutality of the world and must harken back to his human upbringing in order to convince himself that it isn’t his place to be a ruler. He is surrounded by a whole world full of people but must feel totally alone, separate, alien. People are so unbelievably fragile to him that, even though he makes it look easy, he can never forget that he is different and that he can’t make mistakes.