I'm still fairly new to quilting myself (have about 5 or 6 pieced quilts made so far) and I've only recently started on a quilt that came from a pattern! And I'm only using the block layout, not the overall quilt layout they have there. It just doesn't suit me like MY version does!
I really enjoy the pattern-making part of quilting. I sit down with my graph paper & color pencils and have fun. Or I mess around in EQ ("Electric Quilt" - quilt pattern making software). Actually I usually design blocks on graph paper and then remake it in EQ to play with overall quilt layouts and colors.
So I think it depends on the person's preferences more than the skill or experience level. For me it's kind of a "quick fix" when I want to be creative. I can "make" a quilt on paper a heck of a lot faster than I can sew one up! LOL