Why is it important to study the plate motion on earth?

You'll be familiar with the concepts of the super continent Pangaea, which lasted from 510 million years ago to about 200 million years ago. This split into Laurasia and Gondwanaland, with further breakup and amalgamation occurring since then.

This super continent 'amalgamation and breakup' has occurred at least two times earlier in the History of the Earth. [Rodinia and Columbia]. This has profound influence on climate and bio diversity and extinction.

These huge changes are mainly caused by the heat from the Earth's interior, via the mechanism of Tectonic Plates.