if the quilt is to be used as a bed cover (blanket) I would definitely quilt it. You grab the edge of a quilt to pull it up when you get chilly in the night.

your batting will tell you if you have to quilt it or not, but you need to at least tack it down here and there no matter what type of batting you use.
the package will tell you if you need to quilt every 2-4" or if you can quilt up to 10" apart, so if you have the every 10" (warm & natural) then every 10" or less you need to have quilting. if you are using a 2"-4" quilting batt (hobbs heirloom) then every 2-4" of the quilt needs to be quilted. and the package will also tell you if it is a good choice for tied quilts.