Why English is called Language Arts in America?

In brief, Language Arts is the study of English Literature, classic through contemporary, as well as the formal science of its rules of use, called Grammar.

Also,

Some instructionists - non-teaching ed biz professionals - seem to think that more syllables are better than fewer syllables when describing anything. "Language Arts" is harder to say than "English," so it must be better. There is also a kind of Tea-Potty jingoism that holds the term "English" insufficiently American-sounding. Finally, there is a certain recognition that most for Americans, English is a blunt instrument.