The problem is they are far too complicated to explain to voters which makes them unlikely to be adopted and unlikely to be trusted. Having a secure vote is obviously the primary goal, but having a vote that people trust is pretty important too.
This system was designed by a couple cryptographers, one of them Ron Rivest of RSA fame. For details on this and a couple other simple voting systems, see here:
'DOZENS' OF COLORADO ROMNEY VOTERS CLAIM MACHINES CHANGED VOTES TO OBAMA
Actually, he'd be much less credible than an anonymous 4chan poster without video.