Maybe it’s just me, but out of all RPGs i’ve played those with a lot of customization options were generally less immersive than those where you had just one predefined character. I don’t know if it had anything to do with the player character or if it was just a coincidence, but it’s something i’ve noticed several times.
One example would be TES:Morrowind vs. Gothic. Morrowind came out about 1 year later and had much better graphics than Gothic, the world was a lot bigger, and there were tons of random NPCs everywhere. But in my opinion Gothic 1 was a lot more immersive and less sterile than Morrowind, even though Gothic has no character creation at all. The player character doesn’t even have a name!
Still, when looking back…
i remember the names of all important characters in Gothic, but not a single name of any character in Morrowind.
So personally i really prefer characters that have a personality. Not just the player character but the NPCs as well, i like it when they can tell you their story. In my opinion that’s way more important than having tons of soulless interchangeable NPCs