Yeah I agree with your points but him not being able to see colors is not something he should've actually been born with, it's actually a curse done by magic. If it was a natural occurence (a genetic disease to be exact), the emperor wouldn't see him as a dangerous boy therefore wouldn't even try so hard to cure it.
He's suffering because of this curse because everyone's believing in the stupid prophecy that's why it's important for his curse to be lifted, then at least he can prove that he's no more a cursed person who'll destroy the empire. Lifting his curse will be an indication that he won't bring destruction
Ι actually don't have a problem with the art, but with the story itself. I tried reading 2-3 chapters and if you ignore the ending the story is decent. But I can't. The poor boy is color blind and instead of focusing on him learning to be functional with his disability the author has written a story about how love makes him suddenly see all colors, as if being color blindness is something that needs to be fixed. It's basically the same premise as having a person of color as the male protag and the FL tries to make him white, in order for him to be accepted into his environment.