> You have a device that's utterly useless except in close proximity to its parent, why wouldn't you just plug it in and never have to charge it?

Wireless mice aren't convenient to keep plugged in with many laptops in many carrying cases/bags/etc, and having to plug it in increases the set up time before useful interaction. So, for laptops typically used on-the-go, I see them as a negative.

And, mice can be useful fairly distant from a CPU; they usually aren't useful far from the keyboard (which can also be wireless) and, depending on the display size, may need to be close to the display.

I mean, its not like we live in the era when most computer use involves switching disks or other similar activities that require physical interaction with the CPU case, so there's no particular requirement that the CPU needs to be that close to the keyboard/mouse for the setup to be useful.

That's a good point w/r/t desktops, you could easily have the CPU case hidden away down behind the desk or something, but the parent comment said "especially on a laptop" where the monitor/keyboard/cpu are somewhat bound together.

I guess you're right about the setup time, but that seems like an extremely minor irritation to me, compared to the moderate irritation of swapping out or recharging dead batteries. Ultimately, I suppose it's a personal preference: Do you prefer a tiny annoyance every day, or greater annoyance (still negligible, in the grand scheme) every few months.