I think a lot of people are confusing levity and humour with "fun" (and in the process grossly oversimplifying the situation) Take Mad Max fury road for example, a film with little to know laughs or quips but youd be hard pressed to find any film that fun.
BvS was badly written and worst of all badly paced, therefore a little levity and humour would have helped it...but it wouldn't have stopped it from being a bad film, actual exciting moments and decent writing is what would have saved it. Suicide Squad can be as grim as it wants, as long as its got exciting scenes and great writing then no one can fault it. So this idea that jokes = good, is flat out wrong.