486dx/sx anyone? Here the maths coprocessor was not wired up in the budget version. Yield had as much to do this as marketing.
Lame Teslas. If you want auto drive and to use all those battery cells then pay extra. The mass production can be extra efficient plus upsells are possible as the customer can pay for the upgrade later.
1000 hour light bulb. The cartel of lightbulbs required bulbs to last a lot less. Worse product, more repeat sales, rigged market.
The smaller chocolate bar. To hit a price point, e.g. a dollar/pound/euro the product can be made worse or smaller.
The cheap board game. Times have changed, people play a board game once and it goes in the bin. Before TV the product would have been played year round and passed on to the next generation. There is no need to build a product to that standard any more.
Patents expire too, this means products get worse.
Changing laws. Imagine that you can no longer use bright food colours, the product gets worse.
This article didn't address anything I didn't know of and made no mention of what is obvious.