DC doesn't want to earn that 1.5+ billion dollar ensemble
I think they wanted and were chasing that 1.5 billion dollar box office ensemble super hero film money so bad (like the avengers) that they somehow missed that that was only attainable by first doing some solid groundwork and character development in solo films and creation of a complex universe.
iron man made 500 million. iron man 2 628m, Thor 449m and captain American 350m. there's a reason there are literally almost ZERO ensemble films released (except superhero ones) in general not just superohero films. you normally focus on 1 or two main characters and a protagonist.
it would of been perfect. do the superman, then wonder women, then a batman solo film and maybe a cyborg or martian man hunter. Now we have well established characters we actually care about. There are now massive stakes when Batman and superman fight. you can even setup the fight a lot more and better, while also showing us a badass detective more grizzled bruce Wayne.
there just isnt enough time to develop 4 or 5 characters in a single film. its basic filmmaking. but DC couldn't be patient. you think they've learn from bvs, suicide squad, justice league and now this