Don't call your mother fat, don't push the person standing at the crosswalk in front of a bus, don't cut someone's hair when sitting behind them because it bothers you... Socially unaccepted actions, why, because they are. In another universe they all may be acceptable. Our cultures calls them rude, murder, and possibly assault or maybe just impolite. Why. Because stuff and things. Mostly, it'll hurt someone's feelings.
Really I think it is, our freedom ends where anothers begins. Thus, we are free to do what we wish, but if your happiness impeeds on anothers happiness, then there is an issue.
Edit*. When the law doesn't match that, then I feeo government has failed