I never can tell with these places if it is that they changed the recipe (certainly likely--due to cheaper, cancery ingredients), or it is just my memory of my teenage and younger palate simply not agreeing with my current adult palate (also likely). I think it is something of both.
Even so, in those days when I considered Pizza Hut superior in their class, I still recognized Domino's as crap, Pizza Inn as crap, CiCi's as...uh, re-purposed prison food, Gumby's as crap (OK, except for those 3AM Pokey Stix! nom nom nom), so at least that palate had some discretion. I haven't tried Pizza Hut in years, but I always loved their "Deep Dish." No other comparable fast/delivery pizza joint had that kind of pizza.
Recently, I tried Taco Bell for the first time in about 15 or more years...maybe 25 years. no idea. I remember it being delicious, as awful as it truly was, but I at least could crush about 4 or 5 tacos at a time back in the day. ....but these tacos that I recently had, no longer any kind of value at nearly $2 each (remember when those things were like, $0.59 each?), tasted of sawdust and cold. Truly, truly wretched. I am told by lifelong Taco Bell aficionados that "nothing has changed," but I definitely can't be asked to stomach that again. Could be that it was the Taco Bell in the Student Union area on campus, but still. The Chik Fil-A there holds court really well and the Panda is, well, just as you expect of any other Panda Inn. ....
Anyway I think it's both: very likely that they have cheapened out on recipe to target the even more $$$ conscious demographics, and memory of the old days really isn't as good as it was. Still, Domino's is observably better than they were, and they improved on purpose. So there is certainly a management decision somewhere to intentionally make things shittier