Nearly every game allows people to type in their own name for a reason.
You'll be pleased to know that this game allows people to type in their own chosen name, too.
That's why when you get someone else's save, you also get their name.
They chose it, at the start.
Simple answer, really: If you want to choose your own name, use your own save.
It’s pretty understandable why people would want saves to skip these boring grinds when they’re just trying to tap to porn games.
If you believe that to be the case, well, using the same logic, you could also say that it's pretty understandable why a dev wouldn't want to code something into his game that meant players could avoid playing it.
Maybe he thinks that players who just want to skip through his story, to simply see the sex scenes, are intentionally missing the story he has spent time & effort trying to tell.
Maybe he finds that insulting, professionally?

Pretty understandable, indeed, why a dev wouldn't want to spend additional time and effort, over the standard development, to create something extra which enables people to not play his game.
Would be kind of dumb, if he did, when you look at it like that.
Would you like to work for a month to produce something, then have to work an extra couple of days to provide a way for everyone to ignore 90% of what you've produced?
I certainly wouldn't.