First they question all of the underlying myths involved with the fairy tales which have confused humanity for centuries. Act two is full of questions about unfaithful husbands, common ground to establish relationships rather than appearances, and the sheer difficulties of life that require a good nurturing childhood to help people cope. Rapunzel, locked in a tower most of her life, could not handle the stress, and commits suicide. Red and Jack each face a trauma which affects their growth from childhood into adolescence. The wolf may be slain and the Giant may be dead, but that does not erase the pain.
People are who they are because of what they have experienced.
Finally to condense a very complex psychological puzzle, the four main characters realize that they must stop blaming others for their troubles, stop expecting someone else to solve their problems, and begin taking responsibility for their lives. They form a non-biological family, a community. They create a new world. The Nineties are too close to attempt much of a generalizable analysis by decade, but Sondheim has begun his Nineties work with two musicals, one with James Lapine and the other with John Weidman. Each offers an interesting societal challenge, and certainly no one could suggest that his work has become softer with age.