Because it's "unpresidential", which is hilarious when you see insane people working as therapists in California and those same people stay quiet about it.

Who cares if the President swears? I wouldn't have cared if Obama swore as much as a sailor if he at least did good things for the country, the President's job is to lead and improve a country, everything else is just part of that person's personality and has nothing with what a President is.