And what exactly makes you think that Ubuntu doesn't meet that goal whereas OS X does? The fact that you are an OS X-fanboy?
Last time I checked, Ubuntu works just fine.
Partially off-topic but... Want to know wht is the absolutely WORST thing of being a Mac-user (which I am)? It's the other Mac-users. Too many of them are rabid fanatics who see absolutely no value in anything else that Macs and OS X. It's the Mac-way or the highway. OS X does something in certain way, and some other OS does it somewhat differently? The other OS sucks, and OS X is the only true OS.
Seriously: my OS of choice is OS X, but I also like Linux, and I'm a paying member of both FIMUG (Finnish Mac User Group) and FLUG (Finnish Linux User Group). And I must say that while the Linux-users dislike Windows and Microsoft due to all the unethical stuff Microsoft has done, they do not hate Mac-users or OS X. But I see all the time Mac-users treat both Windows AND Linux with utter contempt (well, folks in FIMUG are nice bunch of people, I'm not referring to them). It makes me annoyed and it makes me feel ashamed of Mac-users. I really see no reason for that kind of behaviour. Maybe it's due to some internal sense of elitims or something, but it still doesn't make it acceptable. If PC-fanboys are like schoolyard bullies who are teasing the "little guy", Mac-users are no different. They get picked on by Windows-folks. And they then in return attack the Linux-users.
Someone on these forums once said it best: "We Mac-users hould remember that Linux-users are righteous as well. They actually make the conscious decision to use a system that they like, instead of just using a system that is given to them". Really: keep that in mind. Linux could be one of the biggest allies Mac-users could have, yet it's routinely treated with contempt. Most of the Windows-users are mindless drones, very few of Linux or Mac-users are. There are more things that connect Mac-user and Linux-users to each other than there are things that connect Windows-users to either Macs or Linux. Yet Mac-users are doing their best to alienate Linux-users. And there really is no need for that.