We have the USS Archer (three ships from different time periods), the USS Chekov, the USS Cochrane, the Gorkon, the USS Hikaru Sulu, the USS Janeway, and shuttlepod Pike.
So, yeah, it happens a lot. (Also, given that Uhura was a senior staff office on one of the most prolific starships in the fleet's history and played a role in numerous historical events, it's very logical a ship would be named after her.)
Irrelevant.
You say that like it's a bad thing.
It appeared in "The Star Gazer" [PIC]; it's canon. Also, in the past, ship and class names and registries used in the scrips and reference material will be used if and when one is needed for a line of dialogue (case in point, registry numbers made for the Star Trek Encylopedia were used for the remastering of TOS and the Miranda class -- the official name for the Reliant's design -- has been consistently used on set dressing ever since it was devised for the reference material). Long story short, if and when this ship is called anything in canon, dollars to donuts, it will be called the USS Uhura NCC-90214.
Irrelevant.
It's better if we just agree that there's no good reason to decanonize it.
You have yet to make a good argument on why it was a mistake to establish that Uhura became a captain and had a ship named after her and everything in canon is not only consistent with the idea, but supports it. Your only argument is that you don't like the idea. That is the question, not whether a canon fact is or is not canon.