They shouldn't be expected to, but if they opened up the Mac OS to other hardware then Apple's market share would skyrocket and could very possibly overtake Windows someday.
The last thing any OS X user in their right mind would want is for it to become a Windows clone. There goes nearly every reason to use OS X. Right out the window.
This "open up OS X" garbage seriously has to stop. It's bad business from every angle, and it would certainly be a colossal disservice to the average user.
Besides, No one, that is, NO ONE in their right mind selling computers or software in the current market is interested in seeing a legal precedent set that blows a hole in the principle of the EULA.
Apple succeeds spectacularly with Macs and OS X precisely
because it's a closed, controlled ecosystem. Anything else (or anything less), and OS X becomes a Windows clone. And who the hell would want that?? The whole reason behind Apple's business model when it comes to Macs (and their resulting success) is that OS X is tied to Apple's hardware. This is the reason customer satisfaction rates are so high, year after year. This is the reason the also-rans of the industry aspire to render their products more "Mac-like" in every way possible.
This "freely use computing hardware the way they want" and "open up OS X" notion lives and dies in small corners of the internet, and in the even smaller corners in which Apple fan sites live, fuelled mainly by the geek/tech-enthusiast minority that (wrongly) thinks it knows whats best for everyone else. In fact, Apple knows best. Period. The proof is in the numbers. Hackintoshes and mucking around with the OS and wailing about "freeing" it is alright for that small segment of Apple's user base (a segment which in the grand scheme of things is inconsequential anyway), but it would be a monumental disservice to the average user.
Apple succeeds because of these specific differentiations. It's a coveted business model that others only wish they could emulate successfully. We're at the point now, where if the average user has $1000+ to spend (and apparently, plenty of them do!) a Mac will be near or at the very top of their list. That's quite an accomplishment. It's the reason Ballmer ends up looking stupid, flustered, and tongue-tied at press conferences, especially when he's in a room-full of Macs.And by the way,
the last thing Apple's numbers, record Mac sales, and dominance of consumer mindshare and opinion would suggest is for Apple to opne up its OS. There's simply no demand for that and no reason to do so, especually when Apple's making headlines, dominating mindshare, #1 in satisfaction surveys and reports year after year, the darling of the tech industry, and defying the recession with its current business model. Do you think Apple would be stupid enough to let go of all that??