It's a limitation of battery technology and not really anything Dell-specific, though I wish they had included a cosmetic battery-compartment cover so that the unit could not only be operated without its battery, but operated without having a exposed trench in the bottom of it, if you follow me. =) At least that way I could have followed the advice of battery nerds and stored the battery elsewhere when I wasn't using it. This defeats a lot of the convenience built in to having a notebook in taking away its grab-and-go functionality, but at this time it seems like that's the only way to ensure decent service life for one's batteries.
Diversion: I Enjoy Being a Battery (The Onion)