Carelessness or revisionism?
Considering that other one comes from "Year of Hell", I'd argue revisionism is sort of built in.
Basically, the later map gives 70k ly from Ocampa to Earth, and 130k ly from Ocampa to Earth via the Gamma wormhole. So by going for Gamma, the heroes could shave about ten years off a voyage they will never complete themselves (except perhaps for Tuvok) in the best case scenario. OTOH, if that one didn't
pan out, the additional 60 years of travel time probably wouldn't mean much for our now deceased heroes, or to their children or grandchildren.