My opinion? If you can't define it, maybe it doesn't exist.
I belonged to the local MQG chapter for a while. It was a small group (as in fewer than 20 members) and I liked the other ladies, who were mostly younger than me. Because it was a small group we didn't have the resources to hire speakers, so members of the group did demonstrations or classes during meetings. As one of the more experienced quilters in the group, I led several of those, not teaching "modern" quilting, but introducing the other members to different types of quilting. Most of them had no concept of the many different types of quilts that peacefully coexist and are appreciated in traditional quilt guilds and quilt shows. But after a while, I realized I wasn't getting anything out of the meetings. Then I realized that dues for this very small group were higher than for any of the other guilds in the area, and the reason was that a substantial portion of the dues went to the parent organization, which provided no services at all to the local guild, other than an online presence. I went to the MQG show in Pasadena and was generally unimpressed with the quality of the quilts, even some that had won awards.
The word "modern" bothers me. Vintage Amish quilts show the simplicity of design and large expanses of fabric in many "modern" quilts. Improvisational piecing existed long before the modern quilt movement started. (At one of the MQG meetings that I attended when I was still a member, someone showed a quilt with improvisational piecing. The members seemed to think this was something new that belonged to the modern quilt movement. At the next meeting I brought in a vintage quilt, probably from the 1930's or 40's, done entirely with improvisational piecing. I'm not sure anyone really got the point; it wasn't made with fabrics that they recognized from current designers.) But the thing that probably bothers me the most is that the modern quilt movement can be very restrictive. There are many types of quilts. I don't make make them all, but I appreciate them all. New quilters who get caught up in the MQG movement and only go to MQG shows aren't being exposed to the incredible diversity in quilting.