Doomsday reveal neutered all the excitement and tension of a Batman v Superman fight since we were shown they're all chummy.
Yes we knew they'd join forces but seeing it made all the hype about their fight evaporate.
Since then they've kept Doomsday away from the trailers and hyped up the fight again and it's been to the benefit of the films exposure.
I honestly don't understand this train of logic. If you KNEW and yes, everyone knew, that they would join forces by the end of the movie, why does seeing 1-2 scenes of said moment ruin anything? Do you have that little imagination?