Because people don't expect the iPod to require a particular version of the Mac operating system. Do you, personally, *ALWAYS* read requirements. You _never_ expect something to simply work, out of the box? There was a time when Apple was proud about things working out of the box. Nowadays when you buy an iPod, you have to meet the minimum requirements for hardware (USB 2.0), operating system (XP sp2 or Tiger) and iTunes (which you have to download yourself). Btw.: If you have a popup-blocker on IE for Windows, chances are iTunes will never even download, because someone (stupid) at Apple decided that Windows users (and *ONLY* Windows users, apparently) want a window to pop up before the download starts.
Besides: If you go to a *real world* store and say you want an iPod, they sell it to you. And the small print about the system requirements really _is_ small print.
All that said: Yes, you do need 10.4.8 or higher for new iPods.