It is nice to live in the past as someone has said, it is cheap. But constantly being nostalgic about the past does not help the present and definitely will not help the future if you keep on dreaming of recapturing the glory of the past without much leg work. Many individuals are guilty of it and many countries are also in the habit of dreaming about the past glory of their country that once was. Sometimes I do reminiscent about the past years and I believe many people do but I also not keep on glorifying my achievement of yesteryears and not do anything to surpass that glory. And here is what some people and countries do to sleep on their past glories while lamenting the current state of affairs. For example some old people lament the current state of affairs and long for the time when life was simple and manageable.
In the United States, the current trend I suspect is that to dial back to the time when America was mostly white (I may be wrong but the policies of the government sure makes it so). In the Islamic world, there is still nostalgia about the past glory of the Islamic empire and on it rest the dreams or the fantasies of the Muslims who dream of regaining that glory and to achieve this some of the Muslims have gone to the extreme right and started violent and deadly confrontations with fellow Muslims and Non Muslims to achieve their goal in a violent way. Other Muslims just lament their present states and keep on harping about how great they were before without trying to achieve greatness again with hard work and persistence. But I believe this is not only related to Islamic world as I am sure other countries and culture lament the time past and not happy with the changes that are happening to fast for them to appreciate.