Cheaper to build. Allows greater design flexibility. Gets around the inherent problem with cars, in cab noise, because it doesn't act as a conduit for vibration straight to the hot seat.
Easier to assemble.
Funnily enough, you may laugh, but its probably statistically less likely to fail than the mechanical parts, across a production run of hundreds of thousands of parts.
Altezzaclub, the stuck throttle incidents were mechanical failures; nothing to do with the computer.