Why can't electronic music replace vocals or all types of instrumental music?

Broadly speaking, the term electronic music can refer to many types of music, as the use of electronic instruments has become more common, and much of the dance music of the late 1980s was electronic.

Broadly speaking, any music created using electronic devices. Any electronic sound produced by "instruments" such as synthesizers, effects, computer music software, drummachines, etc. can reasonably be called electronic music.

Broadly speaking, the scope of electronic music is quite wide, including movie soundtracks, commercial soundtracks, and even some pop and rock songs, but it's not easy for people to notice.

In a very narrow sense, electronic music refers to techno, trance, and other kinds of music. In fact, however, as long as the use of electronic devices to create music, including house, drum and bass, and other types of music, and even just the use of electronic amplifiers (amplifier) jazz and folk music, can also be electronic music.

Why we listen to music is not only to listen to the melody, but also to feel the emotion that gives the melody. The human voice, as one of the simplest sounds, is nevertheless the most complex. Thousands of variations, can not say that emotion and vocals are interacting.

If one day all the sounds we hear in the world are synthesized from metal, what emotion do we have left to speak of.

Purely personal opinion, you take your time to feel.