Color is definitely something that catches a person's eye, so if you have a "food product" that needs extra to convince someone to buy it, color is a way to do it. You can't taste it before purchasing. You can see and smell it, so they push those levers as much as they can.
Multiplied by the hundreds of decisions people make every day and now you know why we have the FDA.
People cannot become experts for every decision they must make.
Simple has nothing to do with it. The point is that people ignore warnings all of the time for various reasons. Some people look at the risk/reward factor and decide the risk isn’t that bad. Some people have no idea what the risk means and ignore it. People go sky diving even after having to sign all of the liability release forms, make a video recording while reading a release statement, etc. in Hawaii, there are signs that suggest people to not travel any further due to safety reasons and by proceeding further you do accept all liability. Nobody stops there, and the vast majority don’t even stop long enough to read the sign.
The point being that humans are bad at weighing risk/reward and make bad decisions all of the time.
So in other words: no, we don't need it, particularly since people need to consume less ultraprocessed foods, not more.
Mandate big font "contains carcinogens" label when your food contains this colour. Then let the buyer choose whether s/he finds this shade of bright red attractive or not.