Yes, we want to know your personal tastes so we can factor that into reading a review. Try as you might, they're always going to influence a review, so the best thing to do is be as transparent as possible about your feelings and trust your readers to come to their own conclusions. I don't want a reviewer to tell me they had a fun time playing a game when they really didn't.
The fact that Mario annoys you does have something to do with the quality of the game. It's a feeling that not a lot of people share. On the other hand, a lot of people do. If you were articulate in your writing, you'd be able to explain why, so that even the people who disagree can understand your views.
Or you can hide your views, whichever.
There's a large difference between hiding my personal taste (which I don't), and telling my readers that a game is bad when objectively it isn't.
The second case misleads the reader (even more so if you hold the responsibility of going on metacritic) in believing something untrue, and it's something a reviewer should avoid.
The fact that mario annoys me doesn't have to do with the quality of the game. It has to do with my personal taste. I strongly dislike cutesy, overly comedic characters. It's the same for Animal Crossing.
Yet both franchise (exactly like dragon's crown) have very strong objective qualities that should (and do) overshadow my personal taste.
This doesn't mean I won't mention my taste: When I feel it's relevant I will, but I won't tell my readers the game is bad because of it. Simply because it isn't.
This is even more serious (and rather disgusting) when it isn't a matter of pure personal taste, but a clear (and openly declared) political agenda.
Ultimately a review editor should not assign a game to review to someone that has open preconceptions about elements of it, unless it's well know that that writer is able to look beyond said preconceptions.
In this case the writer wasn't able to, and the review editor probably gave her the game to review intentionally in order to generate controversy and traffic, which I personally find disgusting.