I could list dozens of reasons but at the end of the day it comes down to having the option and making the choice, instead of having it made by some company. And as someone who repairs their own phones, 3.5mm jacks really don’t take a lot of space. It’s definitely not enough to make a substantial improvement to battery size. You question the point of having them, I question the point of removing them when they were (and still are) a universal standard with not many downsides.

I always prefer wired in most circumstamces; wired earphones, Xbox controllers, printers, etc. I just want something to be the exact same every time I use it so my life is similar. I don’t want to worry about swapping out batteries, or recharging and then then the battery eventually dying. It’s just one extra thing that you have to worry about.

Not to say the newer specs of Bluetooth aren’t great because it has come a long way. And I do have an 1st MX Masters mouse that I love. Idk I just generally prefer consistency and reliability over the ergonomic and mobility advantages. Everyone is different I guess