Why would you ever want someone to unsubscribe from you emails? If it keeps them from hitting the spam them, then I think you would. Sometimes people just aren’t going to want your emails any more, and that’s okay. A high quality list is much more important than a high quantity list. Someone getting you email every week and ignoring them over and over again isn’t going to help you. What is not ok, is having your unsubscribe process so complicated, or hidden, that the subscriber figures the easiest way to stop getting emails is by hitting the spam button.