With regard to desirability, the glutes are gaining in popularity, however the glutes are far more than something nice to look at. The gluteus maximus is the largest muscle in the body and serves many important functions.
The glutes originate from the pelvis and insert into the femur. The glutes have many functions for nearly all lower body movement. These include hip extension (hip movement when you go from bent over to standing), hip external rotation (stand upright and rotate your right knee to the right), knee lateral rotation (sit down and rotate your right knee to the right), pelvic backward rotation (pushing the upper part of your pelvis backward and the lower part forward), pelvic medial rotation (pushing the upper part of the pelvis to the left or right).
The upper portion of the glute assists in hip abduction (raise your right leg directly to the right) and the lower fibers assist in hip adduction (the motion of bringing your leg from an abducted position back to it original position).