This is just my own personal experience here, but getting rid of Null the Gull would still not entice me into playing villain side. Increased rewards would not entice me to do it either. I play this game to be the hero, not the villain. That is something which nothing suggested thus far will correct. It is not that the story content is horrible or the rewards not sufficient. I just do not want to play the villain. Most everyone I team with regularly feels the same to my knowledge.
People seem to forget this was the case back when the game was live as well. Apart from launch of CoV, villain side was always far less in population.