I do like gray in a quilt, but, like you, I don't particularly like it in that quilt. Maybe it's the picture, not the gray.
I made a quilt for my 19 year old dgd for Christmas that used a dark charcoal gray blender as background, but there were only two fabric, both bright with a lot of black/gray sprinkled in them. It was perfect for the quilt, and my dgd loves it, but I don't see me making many quilts with a gray background.
After I typed that, I realized that I have a plan for a two fabric quilt that uses a light gray as sashing, but it's perfect for that quilt. So I guess I will be making another quilt with gray as a background!