No, in my experience, "taking the anger seriously", when it's over something as trivial as the color scheme of a joke forum, is a very bad idea. It teaches that it's OK to blow up over something that petty. People who go over the top in their reactions to things, generally speaking, are not the people the site needs to bend over backwards for. Just like anywhere else in life. Other folks who don't enjoy the colors very much - among them Esifex, dustyjo and theshim - have managed to show a sense of humor. The community here as a whole is capable of having a relaxed atmosphere without having to shift into Committee Mode over every little thing.
In short, yes, sometimes you do need to tell people to lighten up. Sometimes validating their temper tantrums by "taking it seriously" is a terrible idea.