A lot of things are moving to being wireless, and Apple even discontinued their compact wired keyboard all the way back in 2010. But I’m still using mine.
Sure it does make the desk setup neater if everything is wireless, but I still need a wire to charge my phone and sync it fast (wireless syncing in iTunes is still quirky) and you have the hassle of constantly changing batteries. I’ve been using rechargeables for a while, which save money and the environment, but its still a pain. USB keyboards also help when trying to access boot options to have a wired keyboard.
I’ve been using a wired keyboard for a while, plugging my phone in to one of the USB ports to charge and sync it. That still left my magic trackpad needing to have batteries. I tried to build my own USB power similar to this one, but after failing bought a Mobee Power Bar and leave it plugged in the other USB port all the time, and now have a really neat setup with no batteries: