Ships named after Vulcan cities wouldn't make much sense, since Vulcan still has their own fleet of starships. I'd be interested to know if other Federation worlds are the same. I bet at least Andoria is, because they wouldn't have wanted to mothball their fleet while their most contentious neighbors maintain theirs.

One of the concerns also brought up by characters in the past is that joining the federation would lead to them losing their cultural identity. It's very possible this is part of the problem. Even Captain Vendome, with his entirely Bolian bridge crew, is still captain of a ship named after a city in California.

Hopefully this will be explored as T'Lyn integrates into the Cerritos crew.

It also doesn't really surprise me. With admirals like Buenamigo naming new ship classes, this is what you get. Star Fleet needs to work on diversity among their flag officers