Well, my FIL had a Honda that he never did anything to..... for a reason! He never washed it, cleaned it, rotated tires, nothing! Just kept the mechanicals running. Reason: every time someone washed it, it broke down. Filthy and ugly, it ran great....
That said, there's a certain security in letting sleeping dogs lie. The old ones may be set in their ways and so built up with crud inside that they'll never leak! :lol:
Personally, I would replace them, provided the job is done well, cleaned up, and double-checked. No sense messing around with stuff and putting old stuff back together. You could knock some of the crud loose and they'll be leaking in a week or less..... IMO, it's basically a case of "the might as well" concept....
Good luck!