That's one of those things where it comes down to being aware of the audience for your fictional tale, giving them simple, clear codings to tell one society from another. A ship name that was some made-up alien word might be harder for them to recognize as an "Us" ship rather than a "Them" ship, unless it's an alien name we're familiar with like Surak or T'Pau or Gorkon (which was the name of a Starfleet vessel in canon before it was used for Klag's ship in the literature). And it's hard to get across a ship-name theme (like rivers for Danube-class runabouts and moons for Luna-class ships) if you make up alien names that the audience can't recognize as fitting the theme.
Basically it's the same reason the characters speak English instead of a creole of English (or Chinese) with the primary languages of Vulcan, Andor, and Tellar. The latter is more realistic and balanced, but not as suited for conveying information to the real-world audience for the fiction.
Basically it's the same reason the characters speak English instead of a creole of English (or Chinese) with the primary languages of Vulcan, Andor, and Tellar. The latter is more realistic and balanced, but not as suited for conveying information to the real-world audience for the fiction.