I heard they didn't want it to be functional while charging because then people would use it plugged in all the time. They wanted it to be clear that it takes a little time to charge, then you use it unplugged. Might make more sense if there were battery level LEDs on the top or something. But it's just a couple reminders and then bang it's dead.

It takes a half hour to get months of charge back, so it’s not a functional problem. I think you wanted to have a wireless mouse with a port in the back so it feels like a wired mouse when you want it to. That would have been cool but I suspect a standard usb cable wouldn’t be rated for being continually contorted and wouldn’t be as pleasant as a wired mouse wire designed for that, so you’d need a special wire and it was just not going to work.