I'm not quite sure if I should respond, but I hope my perspective helps.
Personally, as a NB person, I would much rather *not* have pronouns impact the story, even in relatively small ways. Not to mention that pronouns don't have to correlate with sex, gender, or masculinity/femininity, so this idea of added realism would actually come at more cost to player freedom. Actually, a gender-neutral writing style feels even more fitting for this game to me, considering the protagonist themselves has a sense of ambiguity, with the cloak and mask they wear most of the time.
I do understand the point about MC's personality, but I would imagine that with limited resources a more variable protagonist would be very hard to implement in a narratively satisfying way, so having a somewhat more estabilished Vesper is a good compromise to me.
For me, my "vespersona" is not me directly self-inserting, but nor do I view them as a completely separate character from myself, and I'm comfortable with that. That's how I tend to view other games with customizable MCs as well, but I understand that it doesn't suit everyone.
However, the point about "plenty of smaller creators managed to accomplish this" just feels needlessly excessive and hurts the message, to put it politely. I hope I'm just reading into the wording too hard.