I think you really hit the nail on the head there. The democrats and republicans have no dramatic difference in policy, abortion is one difference that comes to mind but Dems have proved they won't protect it so they can't really lean on that.

So they have to focus on culture war and aesthetics because they're the same party when it comes to arming Israel, sealing the border, denying healthcare, and generally being the party(ies) of the rich ruling class