If there’s any major fault to be identified, I would imagine it’s the decision that WB took to stick with their original overarching DC plan after BvS got such a slating and made less money than expected.
At that time (March-April 2016) I remember there was a lot of talk over whether the reception BvS got would force them to dramatically change tack and alter their plans for Justice League and beyond. There was an expectation that they would surely have to make some major changes.
They didn’t, and they stuck closely to the original plans (possibly partly because Justice League was due to begin production almost immediately after BvS came out). In retrospect that may prove to have been a bad decision.