It shatters the immersion, and I'm personally tired of this nonsense fanboy dogma ruining all these games, forcing the main character to use a katana. Everyone falsely believes the katana is some god-tier weapon when in fact, Samurai rarely used them in battle, preferring spears, bows, and tachi over it more than 85% of the time. It was only ever relied on as a last-ditch effort because even the samurai understood it wouldn't likely save them. I just feel that a lot of great stories are ruined because as someone who know the facts behind the blacksmithing of weapons, the history or bladed warfare among various things. I will never get over their use, where every other sword would literally do a better job.
Forcing it upon the player in a game where they mentally take on the role of the protag detracts from the narrative and the game. I wouldn't be caught dead using such a poorly made weapon, and I feel that any character that is "me" would feel the same fiery passion as I do.