The two Holidays have different meaning. Martin Luther King, Jr Day is a much more somber occasion, along the lines of Memorial Day. Presidents Day recognizes our Presidents, mainly Washington, who doesn't exactly have the tragic story associated to his life that MLK does. Some Presidents do, but the day is more for honoring the position of President than for honoring any specific one (outside of perhaps Washington). It just has a much different tone.
And I don't know why people would have a problem with Black History Month. It's harmless.








