In a meta sense I get how viewers feel the team doesn't come together to a meaningful way with his return undermining them, but in-universe that seemed to be the point.
Batman realized they were just not enough and decided to absolve his guilt and also bring back someone who stopped an invasion before.
On Superman's side he always just wanted to help and not feel out of place, so it makes sense for him to be a joiner regardless of how it affects balance or whatever. Now, to be clear, I'm honestly not a fan of this movie but I don't hate it, a lot could and should have been done to rethink its approach but I'm willing to let this particular "issue" slide because as I outlined above; in-universe it's not an issue at all.
I doubt anyone in the league was thinking how much better it would be for their character development if they ineffectually struggled against Steppenwolf and then just died. Better to humble themselves, save the day however necessary and develop personally later.
Which is what the epilogue basically shows happening.
Again, could this all have been better considered and conveyed, and a villain and plot as a whole introduced to make more of the "Unite the [Number]" thing promoted? Yes, but as is the right call was made.
Shit, I detest Company Wars and Snyder fans always looking for an angle to make themselves look in the right, but in this case I'm surprised people don't commend a movie for once not doing the "the person who could solve all this is conveniently unavailable right now" thing and just cutting the shit. Does it cheat the audience out of a more weighty ordeal? Yeah, but that's how it goes in settings like this. You either get a more convoluted situation or a less complicated solution. If I can't have better I'll take the lesser of two evils of Superman saving the day there and then in JL over both Batman and Superman floundering about until the last minute in BvS because reasons.