Sleeping bags have some downsides that most people take for granted on camping trips. The hoods are often in the way for side or stomach sleepers, they can feel claustrophobic to many, and, since you still need a pad to insulate you from the ground, the section of the sleeping bag that you’re laying on tends to be redundant weight.
A quilt alleviates these issues. There isn’t a hood, so by using a warm hat or Hoodlum, your head still stays warm, but it moves with you as you move throughout the night. Quilts lay on the sleeper more like a blanket rather than a bag, so it affords more comfort for moving during the night, reducing the cramped, claustrophobic sensation, and eliminates unnecessary insulation and fabric below your body. In addition, by foregoing a full length zipper it makes getting in and out of the quilt much quicker and easier than with a traditional mummy-style bag which is especially appreciated in cold weather and for late night trips.