It seems difficult to me to say what mood this poem conveys. cummings is restating his philosophy that feeling and emotion are primary and reason is secondary. He believes that those who live their lives by reason alone will "never fully kiss you." That is, reason and convention cannot contain emotion just as syntax and form (paragraphs) are portrayed as metaphors for constricting emotion and meaning. So, he, stylistically and meaningfully, is saying that emotion and feeling are only fully experienced if they are not constrained; by syntax or reason. So, the mood seems to me to be either or instruction or annoyance. Reading it, I get the impression that he's almost annoyed at reason, or annoyed at the suppression of emotions. "Life is not a paragraph" - Life can't be described by a reasonable, objective, scientific series of connected statements as you would find in a grammatically and thematically cogent paragraph. For cummings, life is more like formless poetry, with stops and starts, run-on meanings, and many ambiguities subject to different interpretations.