Plato's “hatred”of poetry is ironic and metaphorical. Although he has the poets exiled in The Republic, he would have been banishing himself from Athens if he really meant it. read more
It is for this reason that Plato is considered by many to be a poetry hater. However, that is far from the truth. In fact, Plato favoured and found delight in poetry a lot more than his disciple Aristotle who in turn opposed Plato and supported poetry. That said, poor Plato is still used by poetry haters to decry poetry. read more
Like the other answer, in some ways Plato was opposed to poetry. In particular, he did not like the mimetic aspect of poety - namely that poetry imitated life. This aspect of poetry was seen as opposed to true reality. read more
Plato did not trust art. The arts -- including poetry -- are inferior, mere representations of pure forms, and vulnerable to human error, prejudice, etc. In Plato's view, the arts are the equivalent of lies. Read up on Plato's concept of immutable 'Forms' and his theory of 'Reminiscence'. read more