“Problem” is, it sells.
People obviously want that kind of design features; want the phone to be shiny, bright and good for showing off.
And it’s not like Fairphone-buyers are not exempt from such thinking. Just take a look at the thread where you can vote for colors for the new protective cover for the FP3
But I am absolutely with you, that most people will buy the FP rather for ethical standards than for an unlocked bootloader.
Just my guess of course, as I doubt that there is any evaluation at this early stage. Maybe Fairphone will do some market research later on.