A chair with holes in it can be lightweight, functional, and still comfortable. But do you want to fly in an airplane with holes in it?
Remember that shape is the primary determinant of function, from a molecular level to trains and airplanes, and can be a big determinant of resource use as well. Boeing's new, more efficient 777X features tiny holes in its tail to help smooth airflow around the plane. The end result is higher fuel efficiency. (You can read a detailed explanation at Wired.)
Now add lightweight, comfortable seats, and you'll improve the system even more.