Why does shakespeare include Cupid in Romeo and Juliet?

There is an allusion to Cupid in A Midsummer Night's Dream when Hermia and Lysander are talking. Helena who is there in the scene, says "Love looks not with the eyes but with the mind. And therefore is wing'd cupid painted blind". In this scene, adn allusion is made because the scene talks about love and Cupid is like a symbol of love.