Lots of assumptions of what other people will do when, as you have noted, the Japanese are fine with the brown color. I can tell you that here in the US that there are plenty of folks seeking authentic rather than dressed up foods. And since I cook with soy sauce I wouldn’t have a problem with said fish.

The problem with most food color is that it’s not natural food coloring, but rather loaded with harmful chemicals that directly affect one’s health. Many here in the US are rejecting foods with artificial coloring because they are well aware of the health issues.