On your own words, why do the musical expertise, theater design and choreography plays an important roles in the ballet presentation?

Music, design, and drama have all played important roles in the evolution of dance, and in many cultures dance has actually been inseparable from these arts. The Greek word mousikē, for example, referring to music, poetry, and dance as one form, reflected the integral relation between these three arts in classical Greek drama. In the early European ballets, dance, music, drama, and spectacle were equally inseparable.