I didn't have any issue with the critique of the art, except for the "Art 101 man" comment. As someone who's gone well past art 101, we learn that basic form and space, including shading and perspective, are important to understand, but are not to ever be considered limitations on your artistic choices.
So, though I use shading constantly in my pencil art, I tend to eschew it for my computer graphics. Both are valid artistic decisions.
I find EvaKiss's art to be quite appealing. She is able to use repeated figure poses and facial expressions in a way, combined with situation and dialog, that doesn't feel repetitive.
I can respect anyone's decision to dislike any art style. In the case of this game, I don't agree with the critique. And, obviously, the popularity of the game suggests many others are happy with the style.
Defending my like of the game does not require me to disparage anyone else's views, though.