Re: Legacy stuff isn't the problem.
it is usually flaky after a lot of use, it is usually insecure as it wasn't built with security in mind and assumed that nobody would be able to get through the front door of the network.
Whilst I will admit that older systems may be less secure than more recent ones that does not usually prevent them from being isolated behind interfaces to protect them from the nasty outside world.
As for getting flaky after a lot of use? The software certainly doesn't get flaky. Hardware may fail and storage may exceed its intended capabilities.