Or think of it as a foreshadowing of a touchscreen iMac. I don't think Apple would put a battery in theirs, however. I think most people would be satisfied with just AC.
Honestly, at some point the battery is nice just as a faux-UPS. It's one of the nice things about having a laptop that you just don't have with desktops.
Battery is nice when you kick the kids out of the dinner table and they go to another room... No shutdown reboot. Also plugged in is great at a desk but at a dining table it means a tripping hazard. No biggie but a little battery would be great.