he artist copies things which are not real (because everyday things are themselves copies of the FORMS). Thus he is twice removed from reality and can't have anything useful to teach us. (FORM of bed > Van Gogh's bed > his painting of it). What would Plato have made of a poster of Van Gogh's painting which could then be photocopied and then scanned into a computer etc...? Interestingly, what would he have made of Tracey Emin's bed? What would he have made of the cinema or TV?
This is not an apple.
It is copy of a copy of a copy
and can teach us nothing about apples!
Art also appeals to the lower parts of the soul: it can infect its audience by gratifying their desires, and making them want to imitate it. So, reluctantly,
All art - even Homer - must go.
So you wouldn't want to use poetry to make a serious point, then?