Earlier quoted context omitted.
The problem with belly-up charging is that it's ridiculous quite literally. Maybe usable, but ridiculous, that is all. I think a docking/charging station for the mouse would be more elegant and nice to have, though more expensive too of course.
Even a docking station would suffer from the same problem because people would just put the mouse onto the dock every time they were done using it. Also, I don't think contact charging is as fast as cable charging. The point is to only charge it when you absolutely need to.
That's still so much better than using with the cable attached (if it was possible), or the belly-up charging.