"Colored" became bad, but "persons of color" is fine.
In the end, I don't think there really is any logic to it besides the people being described having control over the terms used. When one term becomes commonplace or starts to have presumptions connected to it, they just demand a new term.
Not so different from sexual identity and gender. The list never stops growing, because the entire point is to not allow yourself to be defined by the most recent term created. You are far more special than that term, and everyone else needs to validate you with your special choice of term.