The Elder Scrolls series was built on immersion. Everything in an elder scrolls game is tediously fleshed out. That ruins? An entire team built that. That book on the table? Yes, you can read it and it actually is a story. A short story but a story nonetheless. Everything in those games is old and has a story behind it. An Elder Scrolls game has an entire completed world. Take Skyrim for example each city has it’s own little world with NPCs just acting out their daily lives and we can observe them and take part in them.
This helps when you have to do a quest where you have to defend another character in the world.. You already care by default because protecting them is required to finish the mission but that’s too cold. A fleshed out real world will help you draw closer to that character and develop a relationship with them. That way when you’re protecting them it means that much more to you because it’s like your own friend is in trouble. This can be especially nerve racking on your first play-through of any game. In games like Skyrim important characters can’t die, but if you’ve never played the game before you don’t know that. The character’s life can be especially important to you.
Contrast this to a game like Fable where everything in the entire world is catered around your character. No one else in the game but your character matters. There are hundreds of characters in the game. Towns have large populations but they don’t matter. They all have names likes and interests but they don’t matter more than numbers do. You can’t get attached to anyone because they’re the exact same. Sure they talk back to you but you hear the same tired phrase from hundreds. You can marry these people but what’s the point? You can literally marry anyone because everyone throws themselves at you.