As has already been alluded to by the Big Pharma and cigarette examples, above, an obvious reason to say "no" to commercials is that all the work we've done to hone our craft and deepen our artistry, all the deprivations we've subjected ourselves to, all the disappointments we've endured, all the mental and emotional anguish we've chosen to invite into our lives---it wasn't so that we could shamelessly shill for some corporation and sell people crap they don't need (and in most cases would probably be better off without). That might be a good reason.