In my opinion, I think the more densely quilted quilts are about texture. The relief areas. And everyone likes quilts quilted differently.
As a longarmer, I have had requests for densely quilted quilts that are beautiful, and those which are sparsely quilted. It depends upon the usage, the recipient, trends, and style of the quilt.
Also, I personally like a heavier quilted quilt. I enjoy the weight and cuddliness of it. However, when I was quilting on my regular Singer, I could not quilt like that - so my quilting was not as dense. I simply didn't have the skillset yet. Now that I have it, I've learned to have the quilting match the style of the quilt and better yet, enhance the piecing. So I have some of both types - the best of both worlds :)
I found in business I had to be flexible to provide all the types requested. Not everyone likes the same things :)