Making, producing and selling erotic material based on manga and anime is a completely legal business, unlike distributing aforementioned material for free through internet communities like this one.
Personally, I couldn't care less seing as I hang here a lot myself, but I do not fancy it when people talk down to people who willingly distribute their art and then tell people where to buy it in case they enjoyed the contents.
Just my 2c to the topic, though, I doubt anyone would care one way orthe other.