Why does it seem like fantasy fiction is always set in periods of time where everything has gone to shit? Why does nobody write when everything was grand and amazing? This happens in all fantasy, the biggest example I can think of is Dark Souls. You're always slapped in the point where everything sucks, and there's all this great lore and history about how everything used to be awesome but we never actually get to experience it
A less orderly, more anarchic setting has more opportunity for conflict, and conflict creates drama, and drama is more interesting to read about than an absence of drama.
Also, ruins are kind of cool.