This isn’t the first post about the color of the route line and the desire to customize it to suit one’s own needs.
I hadn't considered it that important either until today.
However, I was driving in dark mode today and found the blue line very difficult to see against the selected map view.
In night mode, I’d like a different color that’s easier to see.

That might just be my personal view, but perhaps there is potential there for the future after all.