A charging port that occupies the mouse’s footprint
The Magic Mouse’s charging connector sits on its underside, so plugging in a cable props the mouse up and prevents it from gliding normally. The placement makes charging and using the mouse at the same time impractical—not because charging inherently requires the mouse to be switched off, but because the cable blocks the surface it needs to move across.
A design tradeoff, not a technical necessity
The mouse’s top surface is also its control surface: it detects finger gestures, so a conventional scroll wheel and buttons are absent. Apple kept the shell’s upper surface smooth, but the device still needed a physical connector. Putting that connector on the bottom preserves the uninterrupted top; putting it on an edge would make it accessible during use, but would change the shell’s appearance and layout.
That explains the tradeoff visible in the design, not necessarily Apple’s private reasoning. The awkward result is that the mouse must be set aside while it charges. In practice, charging is an occasional interruption rather than a constant one, but the placement turns a routine task into a small reminder that a cleaner-looking design can make ordinary use less convenient.
