I take on board some of what you say, i've been around windows for many years, one of my first IT qualifications was an MCSE so yes, i am slightly biased. however i've spent a lot of time on unix based systems and the like so i'm not afraid of it as some are.
the things i fail to see the upgrade do, which windows would have done, is warn about certain elements 'pre upgrade" as part of its checks, for example "lower levels of memory may cause slow functionality as a result of yosemite being memory hungry like windows vista (remember those headaches!?)" and "print driver not recommended" being another.
The one thing windows always did was allowed you to run the OS on most anything remotely compatible, its issues mainly were a result of being too far stretched to have everything working perfectly as there were so many likely combinations of hardware it was going to run on. OSX however is the exact opposite, if you had an apple printer i expect it would have worked straight out of the back of the upgrade.
Forcing people to either use specific devices (their own!) or face issues has always been apples problem in the market, forcing you to have a technology ecosystem comprising purely of apple products with limited capability to interact with others, including their proprietary cables and connectors etc. along with OS.real techies don't wanna be told what to run the OS or their apps on, or what their machine should be built like, because they built it and its theirs.
when i saw they'd gone to intel i thought "hey its time to give them a try, they're not railroading people any more..." maybe there's some truth in that, but not as much as i hoped. still thought that £1200 at the time, for the spec, was a lot to ask but hey, with bootcamp there's hope if all else fails....
the OS is very reliable in most cases, when i'm in the office i don't ever get a call from the wife to ask what's wrong with the laptop or "how do i do this?" as its very simplistic and easy to use (hence my "children" comment) but as a techie of many years i still resort to a bootcamp windows 7 X64 to do anything other than surfing and reading mails, maybe one day i'll be convinced otherwise, i hope so as i'm not closed minded to change, i'm an architect so i'm quite the opposite!