I think there are two errors in this thread:
- one, lumping all artists in the same bucket; Geoff Tate is an anomaly, because he has shown clear signs that he just doesn't think like other people do.
- two, assuming all aspects of a career are equal, and assuming everyone values each part of that career the same way.
I notice no one has mentioned Billy Joel. He has been pretty candid (and not a little self-deprecating), saying often that he doesn't have any interest in writing new music because a) he doesn't have the belief it'll be as good as what he's already said, and b) he doesn't have faith that people want to hear it. So he tours occasionally, does his monthly "one night stand" at MSG, and is widely regaled as the consummate aging artist.
I don't get the sense that Paul McCartney gives a flying fuck whether his next single is on par with "I Want To Hold Your Hand". He writes because it's what he knows, it's what he's done every day (not literally, I would guess) for something like 60 years, and isn't really interested in the concept of "past your peak". Do you stop breathing because you can't get as much oxygen per breath as you used to?
I look at athletes: they spend every moment of their lives since they were toddlers pursuing a singular goal, then at age 35 or so they are forced to stop, cold turkey. Many athletes don't cope with that very well, because their "art" became something that they didn't just want to do, it was something they HAD to do. I think for most artists this is the case. This is what I feel about Angus Young. It's not about anything other than it's what he knows, it's what he does. Whether it's as big as "Back In Black" or not isn't the point or the intent.