Oh, I wasn't saying that everything just works on Mac (though, really, most stuff does; not being able to do something at all is not the same as installing something and then finding that it doesn't actually do what it ought to have, and your examples point out that the built-in defaults work well enough that you'd like to use those programs for other things that they don't handle by default, too!). I'm just saying that the *default assumption* is that things do what they're supposed to, even if they don't do other things you'd like.
Once you've used Linux for a bit, your (well, "my") default assumption is that a given package will actually not do what it should do, hence my example of not wanting to uninstall the kubuntu-desktop package, even though I'm not using it, because the login screen still seems to be the kubuntu one, and my default expectation is not that it will either warn me or re-enable the Gnome login screen, but that I just won't be able to login without booting into runlevel 3 and fixing things (assuming runlevel 3 is still textmode). Oh, and the pointer and "wait" cursor are still the KDE ones, which is nice since I liked those better, but worrying because it's not clear why the Gnome ones wouldn't have come back.
I switched back in part because I noticed I was using mostly open source stuff instead of Mac stuff, and that was because I could make it do what I really wanted, instead of just accepting the few options I'm given. I knew what I was getting into, because I went the other way a few years back, and I'm not really complaining about that. Also, let me hurry to point out that Ubuntu really has come a long way from Debian ca 2003, but it appears that they've reached this point mainly by making things less configurable so that you're less likely to run into sharp corners, and that once you start doing any real changes to the system, you're on your own. :)