The life cycle didn’t shrink because the quality declined. It was the other way around: the quality declined because the price the consumer was willing to pay declined … since the consumer didn’t intend to keep it for a long time. I see this with appliances all the time. When I moved into my last home the previous occupant sold the washer and dryer to me for $100 because he didn’t want to go through the hassle of moving them. They were still working fine when I moved out 15+ years later … and I gave them to the next owner for free because I didn’t want to go through the trouble of moving them, either.
??? I don’t know what data you are looking at but appliances have leaped in retail price. Use to pay about $500 for an oven and now the average oven is around $1100. Home Depot has tons in the $4000 dollar range. So it is the reverse. Pay more and get less.