I think you make a valid point on the danger posed. However I feel there is actually a greater risk to modernize the system. Right now you can’t reach these machines over the internet. To hack them you must learn the old antiquated languages they were coded in. It’s hard to hack a system that was designed before there was the concept of the internet. Look at all the banks, governments and companies that are hacked with our modern “secure” systems. I think if We remade the system today, I would completely remove computers out of the process except for the self destruct mechanisms.