What is the advantage of increasing frequency?

Higher frequencies provide more bandwidth ; you could send far more data in less time with a VHF antenna than a lower frequency antenna.

Maintaining a consistent electrical frequency is important because multiple frequencies cannot operate alongside each other without damaging equipment . This has serious implications when providing electricity at a national scale.23 Haz 2017

Frequency control is critical to the operation of the power grid . On the grid generation must equal load to maintain a constant frequency. If frequency goes out of bounds then there is either too much or too little generation available.