In other words, they don't like it now.
There's definitely nostalgia wrapped up in childhood trips to restaurants (free Book It pizza FTW) and far lower expectations... I personally find it amusing when people jump all over things being "garbage" like they only shop at Whole Foods or some shit, but there's definitely something to be said for one place being good because it's the only pizza you've ever had versus growing up and trying better, tastes changing, etc.
On my short list of pizza joints, I can think of 3 local places that I'd go to first for various reasons (one in particular is Chicago style and the other two are simply better pizza with unique choices)... and then Domino's, because their crust here is really good and they've consistently delivered a crazy hot pizza that will burn off your mouth.
After those 4, Pizza Hut would probably get lumped into a category with others of being fine if it's offered free somewhere or someone else is ordering... I mean, it's meat, cheese, sauce, and bread, usually difficult to completely **** it up. But, better places exist, at least around here.