Agreed, what are the chances that there is no vulnerability (say buffer overflow attack) that allows a black hat to get into the system?
Swissair 111 crashed because the operator installed a new entertainment system which overheated.
A lot of serious systems made by serious people still end up with stupid problems.
And it might be safer and cheaper to have the option of fixing problems when you find them, because if you don't have that option, you're forced to weigh the costs of a recall against the risks of the issue for every little thing.