I think the main issue with the annual release cycle is not just the annual release itself, but that it’s an annual major release, that is, a release that can break backward compatibility and cut off older hardware. Forcing people to accept that every year can mean your Mac falls off the scales or you need to update your old FM Pro for $500 regardless of actually released feature set just makes a lot of people uncomfortable.
With some annual cycles lately having brought little new to the table if at all (with many pre-announced features not coming until half a year later with some dot update) does for a lot of folks not create the justification for breaking backward compatibility or cutting off older hardware. I personally find that an understandable concern.
Apple could get out of this conundrum by either not breaking compatibility or ending support on a quite annual basis, or by ensuring that there is so much value in the major updates that do, that people consider it a justifiable price to pay for that kind of progress. And, for the latter to work, judging by how things have been going the last half decade or so, it appears Apple needs substantially more time than just 12 months to create that kind of value proposition, IOW in effect stretching that major update cycle to perhaps 18 or 24 months. Minor improvements (not to mention security fixes) could still be issued as soon as they’ve been properly readied.