There’s something many Mac-heads love about Mac OS X, and that’s consistency. Consistency in the UI, consistency in the applications, consistency in how users can perform a large variety of actions in different applications - in the same way. Take a look at Smart Albums: you can create them in then same way in every app (including the Finder) that supports them. Regardless of the reason you want to create a smart collection on your desktop or in LittleSnapper, Mac OS X presents you the same menu.
But when I switched to Mac OS, I just didn’t notice this.
I didn’t even understand why I should actually create smart collections, when the good old normal folder structure was still working fine to me. And that’s the case of many users out there: they don’t get the importance of an operating system that can guide them through the process of having a consistent experience, no matter what they’re doing or would like to.