Here's why:

* Abundance of Silicon and Oxygen: Silicon and oxygen are the most abundant elements in the Earth's crust.

* Diverse Structures: Silicates have a wide variety of structures, leading to a huge diversity of minerals within this group.

* Important Minerals: Many important rock-forming minerals belong to the silicate group, including quartz, feldspar, mica, and olivine.

While other mineral groups are important, silicates dominate the Earth's crust due to the abundance of their constituent elements and the wide range of structures they can form.