Entertainment could also be called arts and entertainment or any number of other names. It consists of things like theater, art, and parks. Essentially it provides the infrastructure for relaxation and play. Relaxation and playing are important aspects of our lives. People will find ways to play and relax on their own, but a community where there is little or no opportunity for shared play/relaxation will be an incomplete or out-of-balance community at best.
Things like theater generally combine commerce with entertainment, which is fine, but there should also be some opportunity for uncommercialized entertainment as well. The reason for this is not simply that some people can’t or won’t afford the entertainment which has a commercial element, but also because I believe there is a different kind of fun when all connection to commerce is removed. Sometimes people just need to get away from commerce.