Up until the point where Superman realizes that Brainiac then destroys those worlds he helped improve i thought it was a good story but for what reason does Brainiac destroy these worlds?
It absolutely makes no sense other than "it's just evil and evil people do evil and illogical things just because..". Is Brainiac then trying to make himself the dictator of these worlds and they resist or what?
Huge plothole and it would have been potentially ruining the whole movie if it were made.
You're reacting to this as though it was the final, comprehensive story of the film. It's not. It's a secondhand summary of a preliminary story outline for a script that was never written. Obviously, if the project had gone forward, the outline would've been refined, more detail would've been worked out, plot holes would've been filled in, etc. Heck, the whole story would probably have changed greatly, since that's how it works in Hollywood. You can never assume that a development-stage outline like this would bear any significant resemblance to the finished film. This was just the seed.
Now however we have one of the best current director/writer teamups doing a new Superman movie and if the Batman movies were any indication we're in for a hell of a ride.
Personally I think Zack Snyder's a poor choice for Superman. He's too much about style over substance, and his stuff seems to emphasize violence and machismo. His imagery is too artificial, too detached from reality, and that's the wrong direction to go if you want to sell a fantasy character like Superman to a general audience. (Which is why I'm disappointed that Christopher Nolan isn't directing it himself.)