I don't know you personally, but it seems some of your fans are being really bitey over the issue of whether someone agrees with your art or not.

But you yourself are not being bitey, and your awareness that you need to improve, as well as that not everyone loves your art, is something to be commended. It shows that you've got ALOT more brains and maturity than to fall into the trap of becoming the Metalocalypse fandom's Snapesnogger :D