Why do Indian movies have to have a song and dance plot?

Song and dance is a cultural practice in India, so there will often be this plot.

Indian cinema refers to Indian films and the Indian film industry, which began in the late 19th century. India is an important film-producing region in the world. India's movie production is the highest in the world, mainly to cope with the huge domestic demand in India. Indian films are also popular in countries with large numbers of Indian immigrants.

Indian cinema began at the end of the 19th century with the first screening of a Lumière Brothers film in Bombay in 1896. Over the next 10 years, foreign producers continued to bring in a variety of new films to be shown in Bombay and other major Indian cities.

These screenings piqued the filmmaking interests of some Indians, and Sadada made two of India's earliest short films, based on the performances of two wrestlers and training monkeys, which are credited as pioneering Indian cinema.