Torah displayed G-d's awesome power and judicious might as He destroyed the evil and protected the innocent. Therefore, when offered the choice of serving or not serving, the Jews individually and collectively opted for service. Service from fear is service, but service from love is not just service, it is love. The service is a reinforcement and advancement of the relationship between the giver and the recipient. He gives without ulterior motive of receiving in return.
Angelic service is pure loving service.
The Jews perceived the purity of loving service that resulted from total subjugation to the will of G-d. G-d granted the Bnai Yisroel their wish. He arranged them in the manner of the angels and gave them flags that identified their individual destinies.