Or even: why not software? Users would revolt, sure, so it's more of a rhetorical question. But the internet is now filled with literally millions of zombied Windows boxes in botnets that will continue attacking people until hopefully the power supply fails. What's scarier is rootable networking hardware (like a consumer switch) that are all solid-state, with nothing to fail.
(This idea is actually due to someone other than me or Adam, but I can't remember who I got it from, sorry... if I had to guess I'd say Graydon.)