As I said, you rarely needed to remember to charge it. Till you would in the midst of something.
Anyway, I never liked the MM so when I had my iMac I bought a magic trackpad (which you could charge while using, small bonus).
To me the plug placement was an inconvenience, regardless of how invisible it is to you.
On top of that, it never charged in few seconds after years of use, mine would take longer just to connect to the iMac again.
I was glad to buy magic trackpad I could leave connected 24/7 and never think about it (also I liked it much more than the MM in general).
People think it will be a problem, so make ignorant commentary about it being idiotic, yet in practice it's fine, and not the worst aspect of a terrible mouse.
It lasted so long, even after the warning, that I never got any urgency.