Hope to hear from others who are more knowledgeable, but I will add my $0.02 that my father is a cabinet maker and in the 70s he made custom enclosures for hifi drivers in our basement as a side job. Not only were those speakers physically gorgeous, they could be played at any level (very very soft or louder than you can stand) with no apparent distortion and seeming perfect clarity. A great deal of attention went into the acoustics of the boxes, the quality of the drivers (this is one area that has advanced significantly since the 70s), and the quality of materials.
I think what has happened since the 70s is that drivers have significantly improved. Unfortunately I feel this has also precipitated a loss of attention to detail with regard to acoustics and enclosure materials. We also seem to have gotten hooked on small speakers, and in the 70s it was kind of understood that you needed some mass in your drivers for the best performance.
So, I'm rather fond of 70s speaker design, and I can see that times have moved on. Is my memory from childhood reliable enough to say that things used to be better? I'm not at all confident enough to say something like that. I just know that I spent decades wth my ear practically glued to my dad's favorite pair of speakers, handcrafted in our basement.