It may be arguing semantics, but there is a scenario where I would "sell a lower quality product". If you have steady sales, but the average ticket price is falling it is an indication that your customers have less money to spend. In that instance I believe you are better off looking for lower cost items to put on the menu. Better to keep your regulars coming in for an inexpensive veggie plate or loaded dog than lose them to fast food joints because your menu is full of twenty dollar steaks but no cheap meals.
I guess what I am saying is that while you never want to reduce the quality your dishes, you can offer "lower quality" ingredients that are well prepared without compromising your cooking standards.