They legit thought that's what it would take to make the game appeal to the US crowd

That's nothing new.
Japanese games get adapted since the beginning of worldwide distribution, to appeal to different markets.
The appearances of characters, number and look of levels, grade of difficulties, grade of depicted violence, nudity...basically everything, that might pose a problem in different regions of the world.

How is having black hair a problem

It's not a problem, of course.

But to answer your question, let me simply quote yourself:

Sometimes that's all that's needed to warrant an (optical) change.

At the risk of repeating myself: that has been done since the worldwide distribution of Japanese Games became a thing (it's also one of the reasons, why some people started importing Japanese consoles and games).

When you age, single grey hairs are more visible with it.

Blond people get to hide their grey hairs longer, as they are harder to detect from the rest of the hair.

This affects also JRPGs, as resolutions increase and you can see grey hair on player characters more easily. With 8K resolutions, you can detect even a single grey hair!

XD

Hmm, I am interested in the game. But still have more catalog to wade through. So, I will wishlist it for now and buy it soon.

Thank you GOG.

I'm sure I will like this more than the first game in the series. Never did finish it because of the sudden change in tone. Had to sneak around an area, and I couldn't do it after several tries.