Let us admit at once - this term is not of the best. Indeed: if there is an easy music which means that there should be heavy? But there is no such thing in the world. Sometimes the music is serious, grim, sad, tragic, but not heavy. So instead of "easy" it is better to say something different. For example, entertainment. Really: that's entertainment music and is the most lightweight, affordable content. It does not cause deep reflection. Her job is to entertain and sometimes to distract, to give rest.
However, "light" and "entertainment" are not synonyms. After all to easy music include operetta, dance music, pop songs, jazz songs. And it is not always just fun. And operetta are such as, for example, "Free wind" Dunaevsky, which refers to the struggle for peace against the instigators of a new war. And pop songs are fun, and there is a very serious, dramatic, thought-think deeply... and jazz is not always entertaining art. And yet lives the term light music. And you have to accept it. Only let us always remember how it conditional.