The game-like reward system of stack exchange may sometimes tempt people to post a question or an answer just to get "imaginary internet points" Should this practise be dis-encouraged?
For some things it might be okay. It's definitely okay to post a question that will get a lot of votes/ traffic for the badges. It's definitely okay to answer questions to get tag badges. More ambiguous is things like Hats, which might inadvertently encourage asking of poor quality questions, which overall removes values.
Bottom line, it's okay if it also helps to build the site, probably not otherwise.