Because his style doesn't work for everything, and he refuses to adapt to other styles.
I mean, look at your own pic, OP. What the fuck are kids doing with eyeliner that heavy? Why are their lips so fucking flat? Why are their noses so piglike?
I won't even get into the sexualization of kids, as they're drawings, but there is that aspect too of why he is disliked.
He can do good art, though. I mean look at that background. Rain on the windows looks great, and so do the lights in the distance.