Calling out using other's work without permission has a useful social value. I can both be a fan AND say that this is a clear violation of IP rights. It's not either or, nor is it bad form to point out when things are IP violations. You may be fine with stealing other people's creative works, but I, and I dare say some others, may not be.
Indeed. I work with a lot of artists, and that's one of the fastest ways to upset them is to use their work for your own stuff you are distributing without permission, free or not. Also, if I were a witty person, I would have responded with:
"How about you focusing on being a fan, and leaving the designing to the designers?"