You're kind of a selfish douchebag artist if you see someone who's a huge fan and is inspired by you and your instinct is to defensively tell them to stop because they're ruining your image, as if your work gives you some right to limit other people's expression. It's one thing if they're trying to steal from you and credit themselves, but they're not.
It also ignores the fact that pretty much all of these games are made by groups of people covering several different disciplines with the goal of shipping a product. You've got an even bigger ego if you're, let's say, the character artist on a project, who feels ripped off by the fan(s) who took the time to learn the ins-and-outs of aspects of the engine that you probably have rarely/never used yourself, but still rely on to do your job. You, as an individual, don't own the entire project: get over yourself.