Not the poster you asked either, but another big reason why the 1980s seems more like today than the 1940s did the 1980s was that the 1960s happened in between the 1940s and 1980s. Our modern world view is greatly shaped by the struggles for racial and gender equality that occurred in the 1960s.
Not the poster you've asked, but I think you might be interested in Mark Fisher's "What is Hauntology?" (10.1525/fq.2012.66.1.16). It argues the contemporary culture is incapable of coming up with genuinely new ideas because postmodernism and late capitalism constraint our imagination to the point where we can no longer imagine a wholly different system of politics and values. We're left with the upkeep of an already established system, and this is reflected in how the present crop of films and music mostly sample and rehash what's been done in the past century.
As a personal addendum, I feel this can be (partly) attributed to the loss of the Cold War's ideological struggle that drove the West to innovate, not just in technology but in societal structures and freedoms as well. This is why it can feel as if we've arrived at "the end of history", the current system has won, so what is left to seek or prove?
Re your addendum and "the end of history": I think it would be myopic for people to think that the current system has won, and that there's nothing left to seek or prove. The current system has brought plenty to many but is destroying our planet, and there's plenty of space for fresh thinking. China is taking the lead in innovation [1]; so perhaps there's a new ideological and existential struggle, just with the US as the underdogs. Hopefully people see this as motivating rather than depressing.
Would you still have these articles by chance? This sounds interesting and is something I "felt" myself.