How to fix flaming and the learning curve in one go:
Implement a tutor system.
A new player joins the game, they apply for a tutor with voice chat to teach them the game. The tutor gets rewards such as RP/Skins according to the rating their student gives them when they hit lv30 and/or based on how long they taught them.
Bad tutors/salty players are poorly rated, therefore removed from the tutor system and receive reduced or no rewards. Good tutors teach the attitude for the community to take in to games as well as provide new players a sense of belonging in the community, and potentially build play groups for people who would otherwise not engage directly with the community.
Thoughts?