Two particular nitpicks that come to my mind are reverse scrolling and automatic termination. Reverse scrolling -- drag down to scroll up -- may be natural on a touchscreen, but why bring it to the PC and switch away from the way you had done it before (and everyone else does it)? Automatic termination -- shutting down apps in the background without asking you -- also makes sense on a mobile device, but is just a bad idea for computers.
By themselves, these kinds of things don't mean much, but these sorts of decisions and some coming mntn lion "feautures" seem to show a pretty clear trend of bringing mobile-inspired features to OS X, regardless of whether they make sense in that context.
With respect to scrolling, clearly how everyone else does it doesn't matter to Apple, since they are willing to change the way they have always done it. So why did they do it? Because it makes obvious sense on a touch device, and because there is nothing wrong with it on laptop or desktop. The annoyance lasted about 5 minutes for me.
As for the automatic app management, why doesn't this make sense on OS X? Because that's how it has always been done? Again, not at all persuasive. And honestly, the OS has long been responsible for resource management, why shouldn't it terminate and launch apps transparently?
I think though that you and many others are missing the point about transparently terminating and restarting apps. It is just part of being able to restore ones workspace after a restart, which is itself just part of creating a seamless pervasive personal computing environment.