People are stupid. I, for one, can't remember where I put my car keys half the time. You think I would be able to keep track of enough things to make any kind of decent program in a multistate computer? hell no! All of this magnificent progress you see is because some genius decided to break everything down to 2 values, so that even simple minded folk like myself could contribute. Oh, and there is also noise immunity, that's kind of important. It's the reason that, much to the dismay of Sony Music, even after that MP3 gets copied 800 million times, it still sounds exactly the same. Try that with your cassette tape.
But just so you know you weren't the first person to think of that. This is how gigabit ethernet gets all that information through those little wires. Each voltage level is one of 5 values. 10GBASE-T uses 16 values. If that wasn't enough, remember back in 1992, when you had to wait forever for your dirty pics to download at 2400 bps? Well, if it wasn't for the magic of Pulse-amplitude modulation, that transmission speed would be limited to 300bps.