I won't comment on BvS in terms of a positive ending, but MOS was definitely not positive. Now it did try to trick people into thinking that it was uplifting, but for me -- and most of the audience reactions I read afterwards -- it failed completely at that. During the early parts of MOS I found scenes cringe-inducing, insulting, and boring, but when the climax came and Superman kissed Lois in the middle of all that carnage, it was so tone-deaf that I was in full-blown "What the hell? Who in their right mind thought this works?" mode, and literally screaming WTF's at my television. I fully expected Superman to stop the kiss, go and pull a wedding ring off some nearby corpse's finger, make a joke about how they wouldn't be needing it any more, and then offer it to a smiling Lois who responded with the words "How sweet and thoughtful of you Clark".
Yeah, it was that jarring. I have crowned it the most inappropriate celebration in movie history, and it is a legendary ending the likes of which can (hopefully) never be outdone.