Decorative coving has been used since the Egyptian, Greek and Roman civilisations. It became popular to have cornicing and coving inside residential homes during the Victorian times.
Cornicing and coving was a design statement. Ornate covings meant you were wealthy and grand and the Victorians loved to show off their homes to visitors.
Today, it is still used to enhance the features of a room but they can also be used to hide pipework and make vast rooms and high ceilings, smaller.