Whenever someone mentions superheroes there are a few that instantly come to mind Batman, Iron Man, Spiderman and of course Superman. However there are some heroes that need to stay in comics and games instead of being pushed into feature films. Superman is the prime example for this for several reasons.
Firstly Superman is extremely over-powered. Whilst he is a bulletproof, laser-eyed, flying, super strong alien it is hard to make enemies for hi to fight in this new dark and gritty world everyone is trying to make their films into. He has no weaknesses apart from kryptonite an extremely rare element. When the hero basically cannot be physically beaten it does not make a great film. Whilst other heroes are just humans with either a lot of money or one power making them unique. Each has their vulnerabilities and has the element of danger, such as Batman in The Dark Knight Rises faces an enemy quicker and stronger than him who could kill him. Superman does not face this sort of crisis as when facing Lex Luthor he outmatches him completely in a fist fight.
Another reason which is connected to the previous one is that it is hard to connect to him as a person even when you have the origin of him growing up on earth thinking he is human doesn't take away the fact that he can't be beaten. Comparing him to Iron Man, Tony Stark may be an arrogant multi-billionaire playboy but having the magnet in his chest to stop the shrapnel is not necessarily relatable is provides them weakness which draws an audience to the character.
Since Christopher Reed as Superman the two reboots of the series and critically been below par on average receiving <7.5 ratings. Comparing this to DC's other big franchise in which Nolan's Batman on average is >8.3 ratings which is a much better rating.
If DC wants to carry on with superhero films other than Batman they need to bring their other creations to life such as The Flash, Wonder Woman or perhaps Martian Manhunter.