I'm a millennial, and honestly there is a lot of truth to what you are saying. My friends and I listen heavily to records from the 60s to the 80s. I remember a lot of cool music growing up in the 90s, and post 2000 you really have to look hard for excellent music. But it still exists.
The difference is that while record companies probably aren't going to own an artist's soul in perpetuity anymore, the economics of music, particularly recorded music are such that few can make it a career. Artist development is not that much of a thing anymore, production budgets are tiny, audio quality is also in a pretty bad state with so many records relying on plugins. I feel more optimistic about electronic artists who can exist exclusively in the digital realm, and that is honestly where most new music that interests me comes from now. Bands tend to be so heavy fried in distortion that I just can't get into the recordings.
People will always defend their turf and get sensitive about generational stuff. I honestly think a lot of it is cope. The reality is that we don't produce true classics like we used to because we don't invest in artists or recordings. I think it also comes with the general decay of culture that happens as commodification and capital eat up everything leaving empty husks. I also wonder as younger people are less likely to own homes, or live in them, that also makes rehearsal a lot more difficult and you might as well become a DJ. This stuff comes in cycles, and I wouldn't be surprised if the next generation of great musicians come from Asia where culture and the economy isn't in such decline.
So yeah, I think you are right that we missed out, but it's always a mixed bag and some things are better now. Boomers had the post-war golden age age where the economy was growing at an enormous pace, a social safety net still existed, homes and education were affordable, and then you had an influx of new drugs etc that made for some inspiration. Our future pretty much sucks, and without that confidence and economic support it is hard to get far in music. But there will always be creative people doing something interesting, and once in a while you get a true genius.