frankness/rudeness

I just don't get it ... why do people confuse frankness with rudeness? I mean, who said that every little thing that you think must come out of your mouth? Like my mom used to say "calladita te ves mas bonita" (= "you look prettier when you are quiet") This by no means equals keeping everything bottled up inside or not being yourself or letting anyone walk all over you, but when what you are going to say doesn't add anything productive and the only thing it does is insult those around you, why even speak? Do they do it because somehow it makes them feel better than others?

Yeah all this stemmed from the Kanye West fiasco at the VMA's last night ... add a Facebook status in which someone vented about his rude behavior and lo' and behold, someone then turns around and acts just like him, no wonder they were defending him ... and sorry, I can't stoop to their level... so let them think they know best ... I know better than that ... "calladita me veo mas bonita"....