I think what e.e. cummings is saying is not that it is difficult to be a poet. I think he is saying that it is difficult to be original - and therefore implying, that in order to be a poet, you must ultimately be original.
He says we live in a world that is fighting to make everybody like everybody else - this is easy. It is easy to imitate others, it is easy to fit in with the crowd, it is easy to pretend to think or to believe or to know. He says it is not easy "to feel" - because in order to feel, humans have to be completely honest with themselves. When this happens - originality can begin to occur - which I believe he is saying is the first step, and by far the most difficult.
It seems that according to e.e. cummings, simply being ready to become a poet is something most people will never experience.