What are the importance of graphical user interface?

For certain applications a GUI is the best type of user interface. These would be most video games, most visual arts programs, and for viewing most modern websites.

For everything else it just is easier for non technical people to use a GUI even though it isn’t efficient and can hide certain complexity of say system administrations and document markup.

It organizes the view into eye friendly focus. It is less tiresome than just reading a black text on a white background or vice versa.