It only went wrong because it didn't know what it wanted to be. It could have either gone a Superman sequel and focused on Superman and Clark more, with Batman and Wonder Woman as more like background characters rather than main roles. And then play up the Supes villain angle and how that changes how people view Superman.
OR
Have it be a full blown set-up for the Justice League and throw Aquaman in there more, possibly Cyborg and have MORE Superman/Batman/Wonder Woman interaction in costume in order to set up the dynamic.
Cause at the moment, it seemed like it didn't know what it wanted to be. It was the misfortune case of being a superhero film with two many characters, too many plots, which became somewhat jumbled.
The Avengers is the example of film with LOADS of characters but never losing place with one of them or feeling off balance. But I do get that the difference being that TA was a team-up film & this was an introduction film.
Its just, we had Superman/Clark, Batman/Bruce, Lois, Martha, Lex, Hollys character, Wonder Woman/ Diana, Doomsday, Perry, etc all with individual story-lines of their own. Its a lot to juggle and I'm not sure they did as well as they could have.
I hope people still remember me, lol. Its been a while since I've posted.