Though jazz theory is not necessary to play jazz, it will be of great help. Some people say that in jazz, you have to play what you hear. I am ok with that.
I am no jazzer, but I appreciate the theories. It helped me to become a deeper player (note: I meant deeper compared to what I was before not to other players). Don't get me wrong, I do not think of theories while I am playing. I use it when I practice. In that way, I be able to truly express myself when I am behind the keys.
Skip theory? Maybe, if you are as talented as the jazz greats. But for those who are passionate to express themselves through improvisation but lacks the gift like the greats, theories will be a great help.
Play what you hear? I wish I could do that. I wish I could easily hear the 32nd and 64th notes in a Thelonious Monk tune (Sir Aya, just correct my spelling. 
). It's not easy to assume the notes that they use especially if you have 88 keys in front of you.
Amateur? Someone has to start somewhere. Everybody started as a student. No one can claim that they just sat down and started playing those complicated yet beautiful tunes. They listened. They studied. They practiced. They have their own set of theories based on their understanding. I believe that once a person try to look out for patterns and tries to understand it, they are creating theories for themselves.
-Nobody is telling anybody to skip theory.
-You SHOULD play what you hear, of course not the fast stuffs you'll learn nothing from just doing random fast things.
-Nobody is putting anybody down.
-No one is here for jazz competition, just exercising the freedom of speech and hopefully be viewed positively, if not... well, that's life.
