But here's the point - you treat poetry as a written form of expression, whereas in the renaissance, and the middle ages, it was an oral form of expression, in the former beginning a move towards the written. The recital then becomes a contemporary construct - back then the poem itself, I would argue, carried more power. In addition to that though, the art of the seduction poem is meant to be written for someone directly, and not to be borrowed (one thinks here of the cheap pickup lines from A Night at the Rocksbury).
Also, I take issue with this concept of "not everyone likes poetry". It's that attitude which makes people not like poetry. Even on this board, there's a bias against poetry, simply because people don't understand it. The reason they don't understand it, is because their teachers don't understand it, and merely hide behind the excuse "not everyone likes poetry". I'm as yet to find someone who actually understands poetry, and doesn't like it. I think this whole attitude in general, and the decline of "liking of poetry" one sees all around them, is simply the product of an attempted desensitization of culture into a void of capitalism - if it isn't a product, I. E. doesn't make money, it has no purpose - and with that comes the stretch towards a pop-culture, built around mass sales, and also pop-literature, and desensitization of reaction towards art. It isn't that some people don't like poetry, it's that some people aren't able to like poetry.
Poetry has been with people since the beginning - it is older than prose, and older than writing. It's like saying someone doesn't like music. The expression through poetry of feelings is the closest one can actually come to expressing feelings. Poetry stretches the actual possibility, bringing it closer to the emotion, beyond any point conversational prose can. It would seem logical then, that poetry would be a good way to express feelings.
Of course, it can't really impress beyond showing "creative power", which isn't reason to have sex with someone. But, like St. Lukes said, it shows a sort of boldness and sincerity, which has its own aesthetic implications, assuming the receiver cares anything about that sort of thing.

