Patriarchal gender norms reinforce a dominance-based social system in which men maintain power by controlling women's freedoms (economic, reproductive, etc) and exploiting women's time and labor. There were certainly gender norms before the onset of the patriarchy, which began around the time we shifted from hunter-gatherer to agrarian societies, but most evidence points to these roles being equally valued and honored. I think in the context of our modern society, we'd benefit from far more flexible gender norms, particularly ones that don't reinforce one gender's control and power over another's.