Favorite trope: Woman who was written only to die/be part of backstory getting their own story and more relevance due to who they were
This is why I loved Batman vs Superman
Obviously they bothered to show us the definitive origin story again, so we have to think why. Most interpretations of the Waynes’ demise, Martha Wayne’s presence is constantly underplayed. Her significance, really, is the fact that she wore pearls and they fell off when Joe Chill pulled that trigger, an imagery that eventually became iconic and immediately associated to the lore of Batman. I don’t have to raise many examples, but one that we all are familiar with: in the Nolan trilogy, Martha Wayne’s influence to her son is almost non-existent. …While in BvS, Thomas Wayne is the one being overlooked. That (gorgeous) shot of the gun and the pearls lingered for a good few seconds — so his mother is what Bruce remembered the most from that fateful night. When present-day Bruce had a nightmare about it, it became apparent that his mother’s passing haunts him more than his father’s: it is Martha’s tombstone that is dripping with blood, it is Martha’s death that contains the demon, all while Thomas Wayne’s name is blocked by the bouquet of flowers.
Let me put it this way: if Bruce Wayne is Hamlet, then Martha Wayne is his ghost. So Martha is important. Martha is the reason why Bruce does what he does, Martha is what he is avenging for — Martha is the lynchpin of Bruce Wayne’s existence, Martha is his purpose, Martha is (literally?) the mother to the idea of Batman. ‘Martha, Martha, Martha.’ If anything can wake him up from this state of confusion and anguish, that would be his mother, his ghost: Martha Wayne (or a mention of that name, as it turns out to be).