Superman is in a tricky position as people expect that if he's around he'll be in charge of the JL as Snyder said in an interview. But, at the same time, producers don't want front and center a character whose last real movie success was in 1980. So, if he can't be the leader and he can't be turned into a "follower" either, he'll be taken out of the picture entirely. Of course, the personal bias play a huge factor in this too.
The way I see it, his forced lack of interaction with the "female lead" Diana is/was part of a larger problem with the current status of the Superman character.