"Well, what possible harm could one insane, mutant tentacle do?"
I generally agree with you, and Microsoft has always been notoriously awful at naming just about anything. The still are.
But Cortana's reputation has been ruined to the point where there's no coming back from it. It was a good name, but a lousy product. From a marketing perspective, it's far, far, easier to start from scratch with a better product than to try to repair the reputation of the old one.
eMule was first released in 2002, as an open source alternative client to the official eDonkey2000 client.
Napster would have technically been a 90's term, since it released mid 1999, but p2p wasn't really a mainstream thing until the early 2000's.
Sorry, I fail to see, how a product that was developed from 2002 until 2017 proves that you lived through the 90's.
Tamagotchi