Installing device drivers...
Ah, but you see, the device drivers that get installed when you plug in a standard mouse or keyboard do not come from the mouse or keyboard itself. Otherwise there I would be having problems using them on my linux box, gaming consoles, and android tablet, which I do not.
There have been documented virusings (That's a word right?) of computer mice and a few high end keyboards, at present only high end gamer parts are really a worry.
I have not found any references to keyboards or mice infecting computers. I'd like to see the article you got that from. If they are though, they would have to be acting as a usb flash drive in addition to a peripheral, in which case you have multiple infection vectors besides just driver installation. A standard mouse/keyboard can't infect your computer simply by plugging it in.
But the thing is, peripherals are becoming more and more complex. Especially so-called 'multi-function peripherals' as this happens they are becomming increasingly less about simply sending and receiving signals and more about processing those first. And plug-n-play means that device drivers can do all sorts of things, not all of them nice.
Plug n play, usually means you follow a standard protocol rather than meaning there are onboard drivers that get automatically installed when you plug the device in. That and the fact that Windows includes quite a few drivers for known hardware when you install it. If Plug n Play relied on onboard drivers, you'd have a lot of problems when you plugged into different OSes and architectures. Also, if the drivers were onboard, you wouldn't have to install specific drivers from a CD when you plugged in a new printer (granted, I haven't dealt with a new printer in a couple of years, and things change all the time. maybe they don't come with CDs anymore).
And if we go to a total plugin model it's going to be tempting to have your shell do more than just accept signals. Go to an internet cafe and plug your computer into a powerful shell that can run those awesome new games people love. How? Just put some processing power in the shell itself. Indeed, how far could we go? What do you *really* need to plug in? A USB that stored your operating system could be plugged into a computer shell anywhere and make it your computer in a flash (heh heh.) And if we utilize the cloud computing system, we need even less.
Now that is an interesting idea. I doubt that is something we'll ever see. We'll probably skip right over that one and internet cafes will be promoting the web/cloud based OSes like ChromeOS.