Are you comparing apples and apples? Many new motorhomes also have nice solid cabinet doors (and other great things), and many older ones had poorly done ones. Comparing a low end rig with a high end rig whether the same or different ages will certainly give different results, so be sure it's a Bounder and a Bounder (or equivalent) or an American Coach and an American Coach (or equivalent) that you are comparing in different years. After all, an old Bounder and a new American Coach will have the A.C. winning on materials.Go to an older motorhome open and close the cabinet doors and then go to a newer motorhome and open and close the cabinet doors and you can feel the difference.
(The above are just examples, so don't get hung up on brands).