Which generally all started with Empire and it's fixation on providing a 'deeper' set of themes and relationships, I'd argue. Which is why it wasn't as good as the original, which was like a cultural breath of fresh air in the cynical 70s by contrast.
In some ways, it'd been better if it had not been quite as successful, remaining a stand-alone movie without any sequels and prequels - go on, admit it.
I like the first movie, but I also don't think the first movie alone is what makes Star Wars so enjoyable after so many decades. I get your point about the cynical 70s, but since I was 1 when it came out, that context is pretty meaningless to me. The first one I saw in the theater was Jedi (which hugely affected me). I saw Star Wars and Empire on TV and Empire is the one that really stayed with me.
Empire is what makes the movies so good in my view. When I watch episode 4, it is mainly so I can get to empire.
But these are subjective preferences.
However if they stopped at the first movie and didn't make any more, I doubt it would have had the continuous impact it continued to have over the years.