Spot on. Democratic process means "owned by people". So the voting system must be able to be run in the hands of the people. Hence the necessity to have it in the form of a simple technology such as pen/paper.
Moreover, having the votes counted in some hours instead of a night doesn't make a big difference, considering the time that is needed for example, to form a government once the vote is closed.
I love computers, but it's not the right tool for this job. It's not much different than free software : the problem here is political rather than technical.