No-one is forced to upgrade, no-one is forced to buy a new Mac. New Mac's come with the same return period so if anyone doesn't like it they can return.
Although a new Mac will come shipped with Yosemite is there anything preventing a USB-boot-blow-away-and-install-Mavericks if required? No hardware has changed with the Yosemite release AFAIK so there can't (yet) be any Yosemite-only support that would prevent it, again AFAIK.
But I'm fairly sure new machines with a fresh install will probably have the lowest rate of issues, its the easiest environment for them to control and should be the most predictable/repeatable.
Maybe not forced, but imo Apple is pushing people to upgrade. Then there's this new iCloud that once you sign up for you can't revert back.
Trusting that Yosemite was going to run smoothly I foolishly signed up and am now stuck, as I had no choice but revert back.
Personally I hoped on the Apple bandwagon, about 6 years back, when I started my own small company and just didn't have time for computer problems. My first iMac worked perfectly with harry a problem. Saddly I guess I hopped on at OSX's Zenith of reliability as I've steadily had more and more issues with each new generation of OSX, thankfully Mavericks was another solid build for me, but now that I've lost my iCloud, and can't update iWork, I'm pretty disappointed with Apple.
Yes, it has affected my 'loyalty' I was ready to jump all over iPhone 6 now, I'm just going to milk as much life as I can out of my 4 and see what happens.
Sadly it seems Apple has just become the lesser of two evils rather than 'you pay more but get more'