I've wondered the same thing! I do know, though, that you can "import" one song/item at a time, though, so it is not limited to an entire library. It may well be the preserving playcount thing, though. I usually use the "add to library" when I have something new to add and it seems to work fine. When I have used "import" in the past, sometimes items would get "lost" later on and I would have to "find" them to relink them to the item shown in the iTunes library in the app.