For an artist to survive, he/she needs to be pretty thick-skinned, especially when regularly posting work to a forum which literally invites criticism. I suggest not worrying too much about the negative comments, and not speculating on the "real" reason you get them. You can't please everybody, and that's okay. You also don't need to rationalize the way you do what you do - if you're pleased with your results then the hell with what anybody else says.