I personally tend to find naming my character less immersive than having a predetermined MC where the devs have more freedom in their backstory and how they interact with the other characters, and that I get to know as the game progresses (unless it's games like BG3 where they have enough of a budget to make the customization feel meaningful). But I realize I'm in the minority here. Lots of players seem to prefer even a tiny bit of customization, for a better self-insert experience.
Anyway it's not a big deal. I just name every MC of every game Protag Onist and get on with the story.
I think it comes down to written character versus conduit. In TW3, you play as
Elric of Melniboné Geralt of Rivia, and regardless of your choices, you still feel like you're following Geralt's story. In something like Daggerfall, the only thing really set about your character is that you've been given a couple of tasks by the Emperor, and beyond that, you're free to create your own character with their own background, motivations, and such. Issues start when the two are mixed poorly, like with Fallout 4—you get to customize your character, but you're canonically either a lawyer or soldier and always a parent, so regardless of what actions you choose, there's still the ever-present specter of "Oh right, I'm supposed to have a son to go find."
The Null Hypothesis handles it fairly well, and while there are predetermined aspects to Null, they all still serve the story premise of "normal guy unlocks his latent power and has to adapt to life as a mutant". Beyond that, Null is by and large whoever you want him to be—the reluctant protagonist who rises to the occasion and shows heroism in the face of danger, the goody-two-shoes who slowly turns into the jaded anti-hero, so on and so forth. My only minor complaint is the backstory being limited to one of three scholarships, but I can understand why the devs went with that. Kind of defeats the point of a dating sim when you can immediately seduce any woman with the single line of "Yeah, I'm forklift certified."