This is just a theory of mine im not saying its confirmed but to play devils advocate(not saying james gunn is the devil but you know what I mean) perhaps he looks at it from the perspective of to bring in another superpowered foe for superman to face, it would be him in a situation we've seen dozens of times in other adaptations(granted legacy is an example of this), powers we've seen a dozen times in other adaptations and you already know with a 99.9% accuracy superman is going to win with the main threat even if he takes some small loses in the film so there isnt as much at stake here so perhaps that is why he is going with a much smaller threat to reduce time and money on big action/cgi characters and set pieces that I wont say are pointless but for most part inconsequential to the main story. That being said I still say if that is the mentality use someone like toyman or toyman and lex luthor cause this whole film feels like superman returns all over again with a few superhero cameos and it wasnt enough at the box office 18 years ago to draw in a sequel so unless the public has warmed up to this idea of a more perhaps character driven drama with little action like superman returns was then maybe legacy needs to be a one and done film with no cliffhanger setup. But what do you all think, am I dead wrong on this theory or do you think I have a point?

And trust me I'd love to see brainiac and darkseid and a whole bunch other of sm foes on the big screen but if my theory is right then I can understand why james is holding back on showing them.