Not harsh, but hypersensitive and looking at it from the wrong way. If a hairdresser or barber says something to the effect of "you would look really good with this hairstyle / hair cut because of xyz OR what do do think of trying “this” style. Doing so is NOT the same as saying “Your current hair style is stupid and ugly”. It’s merely a suggestion based on an assumption of knowing what that person may like and hopefully they’ll be better off, and maybe they will be. But simply making a suggestion of something you think they’ll go for doesn’t mean your bashing or insulting them.
Now if they sat in a chair and the hairdresser said “You just get electrocuted or something”? Fine, THAT’S rude.