Question

Why is energy conversion important?

Answer 1

Because it is very often naturally occourring or requested in human activities.

Explanation:

For example, in the Sun, nuclear energy is converted in electromagnetic energy in natural manner because the system must go to a future equilibrium.
Or for human activities... in a loudspeaker, the electromagnetic energy is converted in mechanic energy and in acoustic wave because we want to hear recorded music or voices.
To close, also a falling ball is a very simple example of energy conversion (potential to kinetic).