Because they are either wholly capitulating to a vocal minority or feel they are part of that minority. In both cases they are stepping on a slippery slope to insanity. The criterion used for this decision is necessarily wholly arbitrary, as what is deemed offensive differs with time and community. Now you have to worry whether your repo with a fortune file with some offcolor jokes is going to be banned. Whether your use of 'retard' for its original meaning is going to cause problems. Whether any other words I use may have connotations I don't know about
