rewiring adding value?

We bought a 1958 two bedroom coop. We are upgrading the fuse box (which has those old round fuses). Our contractor is suggesting we consider rewiring. The edges of the wires that we've seen are frayed, but don't look like they're crumbling, so our contractor thinks we can get away without doing it. The quote is $6000, which seems pretty reasonable, but we'd just as soon not spend it if we don't have to. If it's not crumbling now, and all we're doing is replacing the outlets, are the odds in our favor they'll last another 40 years? Will rewiring increase the value of the apartment on resale? Substantially? Any ideas?