If one thing can come from the first week numbers DC should take away is that people do want to see these characters together.
Even they can look at Berlanti's efforts in the TV version of the DC Universe. The ratings consistently go up for Supergirl, Flash, Arrow, and Legends when they crossover.
People do want to see these characters together. They also just want to have fun and see them be superheros. Not fight one another or spend their films in dour stories about what they should do with their powers. At least not right away.
Batman V Superman would have worked much better if they had Affleck and Cavill at odds after at least 2 or 3 solo films, and one or two JL films, which is why Civil War will work better, there's an establishment of a relationship.