speaking only for my own musical awakening, i went in a quite linear fashion from a pop/rock mentality from the early 60's to the early 90's, to jazz and classical parallel paths with both digital and vinyl starting in 1994. i went from the most melodic and easy to listen to, progressing as i saw it to more complex and dissonate pieces.
i was exposed to Bartok Orchestral early in that process, and i had a hard time getting into it compared to the Romance pieces, but then i did, later. started with the 'easy' string quartets of Mozart and Beethoven, then eventually Bartok and Shostakovich. now i pursue all the modern really complex stuff.
i still don't 'know' any of it, only that my tastes have evolved. it happens that the more complex stuff is more recently composed. but i don't care about that myself. i only know a slight bit about music history, what i've accidently learned. so the idea of musical nostalgia is only regarding my early love for rock.
i do wonder whether my evolving tastes have more to do with me, or my system being more able over time to make them sound natural. which did for a long time involve vinyl, but with better digital that factor is not any more in play. love to explore off the edge with streaming. maybe Joel Durand (classical composer and music composition professor and builder of my tone arms) helped to push me into more complex music as he gave me a list of pieces about 10 years ago to explore and that really launched me.
There are some different points in your post.
1. Your journey from pop/rock to classical/jazz is an increase in musical appreciation and complexity. This is the same point I made to Shane, and it happens irrespective of era. It happens with age for those who are willing to progress on the musical appreciating scale.
2. How you define complex is another question...Bigger orchestral is not necessarily more complex from smaller orchestra, or from chamber musically...as an audition track for system strengths, some orchestral will highlight some aspects of the system as compared to smaller chamber.
3. My question to Al about Bartok and Beethoven was more to do with the fact that someone who passed away in 1940s is not current for us. Let's not pretend any of these guys are modern for us, and appreciating either of them has nothing to do with "being old" - the age here, like you rightly said, has to do with maturity and progress on musical appreciation as compared to Britney Spears. If people of my generation wanted to be nostalgic, they would listen to Madonna, Michael Jackson, and Stevie Wonder's I just called to say I love you on cassette or CD. So on this forum when someone says people listen to vinyl because they are nostalgic, or listen to classical because it is music for the old people, I mark the guy as lacking exposure to good recordings, and lacking exposure to, or not having moved on to appreciate good music. Same for vintage. Nothing to do with nostalgia...actually, for most people today who are into vintage, they found it at the end of their journey (unless they revert), and not at the beginning, to be nostalgic about it (and for me read that as vintage drivers and speaker, not crossover or electronics or catridge).
4. In the 90s, before youtube and internet, it was cool to find bootlegs (e.g. led zep bootlegs) for my generation, because that showed you were willing to scrounge around and were passionate about finding good music. Same for books. The lazy ones just heard MTV top 20, channel V, and such stuff. With YT, some of that went away because you have equal chance on clicking on a bootleg track as compared to a current track. But it stays true for the type of music you listen to, the records you select, and research you do. Anyone can go out to a show today to listen to current performances in their local area...you really need to search across conductors, orchestras, and performances, to find the good stuff. The act of searching alone will develop your skills/taste/appreciation more, and to me it shows a guy who is into it vs an arm chair poster.
5. In the stuff that lives with us, why is classical from Renaissance and classical period, LP records from 50s to 60s, rock from 60s and 70s, digital recordings developing today - why didn't the nostalgic choose the same era for each? It just happened that the best for those respective categories, fell in those eras, because certain factors during that era led to development on that aspect. And electronica might have a different era.
6. I listen only to modern performances live (2 this week, 1 last week, 5 this month). I doubt anyone other than Larry in the regulars here has heard the old performances live. However, I choose the old recordings and performances, because recreating them on a stereo system appeals most to my auditory template of realism...The new ones don't.