If I recall correctly, the film Super Size Me made the point that burger chains' (obviously -- he was talking about McDonalds) products are all so similar that quantity is really the only thing they can compete on.
McDonald's understood the appeal of having multiple sizes of Big Mac, leading to the inception of the Grand Mac and the Mac Jr. Then they got rid of them because they were popular and McDonald's is trying to flatline their business.
The latter. It was meant to be sarcasm; I don't literally think they are making bad decisions on purpose, but they've been losing marketshare for years now and ruining perfectly solid comeback opportunities like that.
There's data suggesting that this model may apply to deep-dish/thin-crust pizza. I've designed a thorough multi-year study to investigate this personally, but funding organizations keep denying my grant requests.