My inclination is to leave well enough alone, as long as it is well enough.
I don't think that minor code violations that might not have been violations when they occurred are adequate reason to worry too much.
I don't think I would worry a whole lot about whether the GEC and GES was in the best of shape, as its role in electrical safety is limited.
I would be more concerned about things like K+T wiring, and 2 wire systems (w/o EGCs) in the house.
I do think it is wise at some point to rip it all out and start over. Same thing with the plumbing and HVAC. Everything has a limited life span.