What makes a quilt "modern"? Probably having the opposite characteristics of a quilt that is considered "traditional". Lol.
I'm with Dunster, the term bothers me. In my experience, certain people who like to use it often sometimes come across as a little... contemptuous. They seem to regard anything not considered modern as less than.
As with ALL art forms, there is room for everything and everyone, and I think exposure and experimentation of all different styles makes all of us better artists and quilters.