While I’ll say there was some rock in the 60’s and early 70’s that was of high quality, in general you haven’t missed a thing. The music you mentioned is and has been superior to the crap the world has been churning out for years. I listen to Classical and the standards exclusively.
I’ve never been much of a Classical fan. There is some (quite little, really) I enjoy; mostly piano pieces. But I had a mentor early on who was a jazz aficionado. That was all I needed to see where my music interest would be.
What you say about early Rock is true also about Country music. I’ve appreciated (and still do) a ‘little’ of both from their early years, but after the 50’s (for me) Rock lost it’s taste for good music. Country also.