If you think the "quality" (any way you define it) of MBs has slipped since 1975, take a look around a our society in general. What sort of "quality" (behaviors) do you see today that would not have been imagined, much less tolerated back then?
Since I'm not adept at time travel I have no choice but to live in the present. I CAN choose my clothes, cars, music, toys etc. and I sometimes choose "oldies but goodies."
My gross pay is now about 6 times what it was in 1975, but then so is the cost of gasoline, automobiles and other toys. If I haven't made much real progress then I can at least be content that I haven't lost any ground, and I spend each day on the right side of the grass!