One charge of mine lasts months, why on Earth would you need 2 mice? Worse case it runs out of battery and you take a 20min break to get enough charge to last you the rest of the day then make sure to charge overnight.
What kind of duty cycle are you using with your mouse? You get several hours of use from (literally) one minute of charging, and if you charge it overnight it will last for weeks.
The MX Master 3 is a wonderful piece of hardware but I personally couldn’t get used to it. I find the Magic Trackpad, though obscenely expensive, seems to fit my needs much better. I used the MX 3 for about a year. I do love some features it has.
If you're a hardcore mac user, I would agree, and even then if you like using trackpads in general. I switch between mac and linux all the time, plus I found using even the MBP 15"'s massive trackpad annoying to use for all-day work, so the MX Master was among the best investments I could've made.
The wheel on the MX Master is brilliant. It’s hard to leave that behind. I think the only reason I couldn’t stick with it was that I need to pan and zoom so often, and the pad makes it so much nicer without compromising too much.
I don't think I have ever cared about how my mouse looks (or how my laptop looks for that matter; it sits at home where no one will see it).
Something you use 8 hours a day should first of all be pleasant to use and reduce the risk of long term damage to your wrist (carpal tunnel syndrome or similar).
I've never found the Magic Mouse uncomfortable to use. I generally use a trackpad anyway. I value that it's portable, looks nice, and works great with OS X. To each their own.
Why? They charge to full in a few minutes and a full charge lasts weeks? You can charge your mouse in the time it takes to get a cup of coffee, let alone a night's sleep?
Leaving batteries on a charger can wear them out much faster than just leaving it in a drawer. This is avoided by "optimized battery charging" on phones/watches/airpods now but I don't know if mice do it.
The issue is that keeping the battery full past 80% is bad for it, but if you're always charging, that implies you always want it to be 100% ready not 80% ready.