I have been doing some testing:
It seems to me that it is NOT the computer telling it to shut off, it is the mouse.
The mouse seems to stop working when power is injected to the mouse.
So there must be some switch inside the mouse that deactivates the sensor when power is flowing into the device.
Because the mouse doesn't turn off or disconnect when plugged into the wall. It stays on and connected to the computer, just unresponsive to movement in the sensors field of vision.
"It takes only two or three minutes to charge it sufficiently for a day's work."
Do you know how you sound right now? When was the last time ANYONE remembered to charge their Magic Mouse? I can tell you right now that no matter how many times I tell myself "Man, I should really charge this mouse", I will never be diligent enough to do it before bed or when I leave the house.
Its simple laziness that everyone is guilty of.
On the other hand, what kind of psychopath is content when they are in the middle of the big project and their Magic Mouse dies on them? No one wants to stop what they are doing, plug their mouse in, and have to come back later. Even if its a few minutes, it will get you by that day. But what about the next day? You'll have to do the same thing again. Again. Again. It gets old. It won't stop until you go "Ok, Im leaving this plugged in overnight"