I like how everyones like "You dont need a gaming keyboard or mouse" then go on to list the obvious benefits of a G19 and gaming mouse with tons of keys that are programmable.
So what exactly is your argument, that a game can be played without gaming keyboard and mice? Of course they can, but as a Gamer I will take higher mouse DPI, 5+ more mouse buttons, customizable mouse weight, programmable keys, no ghosting, a mounted LCD screen, macro keys, keyboard based usb and mic plugs, and a backlit keyboard since they add comfort and functionality.
Unless you can conjure up a terribly good reason for me not to, outside of the fact that perhaps you personally dont want to spend money on these items (which means fuck all to me) I'm not really understanding where you are going with this.