Huh? On non-fast-food cheeseburgers, cheddar is typically the standard cheese, and swiss is also popular. One of the best burgers I ever ate had caramelized goat cheese (in Europe). I don't even know the last time I had American cheese (on a burger or anything else), and I'm pretty sure the cheeses I've had on burgers were not "Americanized" as you mention, they were just normal cheese.
There is a reason that the nationally-famous burgers at Au Cheval in Chicago, Hog & Hominy in Memphis, Holeman & Fitch in Atlanta, Shake Shack in NYC, Husk in Charleston, and probably a bunch of other destination burgers all use American, despite many of these places being sit-down establishments.
And what is that reason? We have Shake Shack here in DC, and the reason there is pretty obvious: Shake Shack is fast food. It's a tier higher than Five Guys, and two or three tiers higher than McDonald's, but it's still fast-food, and their burgers do not cost $12-15 like in nice restaurants, so of course they're going to use cheap cheese. As for those other places, I've never heard of them.
Maybe I'm just weird, because I generally consider fast food to be inedible, so I really don't pay much attention to chains like that. Shake Shack is probably the cheapest type of restaurant I would ever eat at, and that's pretty rare. I make enough money to eat good food.
American cheese is the standard, at the high end and the low end, for burgers that aren't eaten with a knife and fork. The reason is that it has superior functional properties to other cheeses: it remains emulsified when melted, and easily melts completely.
At this point, I'd probably just send to you J. Kenji Lopez-Alt if you want to read more about the virtues of American cheese. It's useful stuff. Ironically, though, I'm here in the thread to talk it down as "cheese". It's a good product. It's not good cheese.
If you're looking for something to serve an almost functional role in a product, like a S'more or whatever, it's... fine? Do you bake with Hershey's? Like in a brownie, where you can dial the sweetness in instead of swinging it all the way to 11?
I don't think there's anything wrong with liking Hershey's chocolate, and I myself like American cheese! I'm just saying they're objectively not as good as other products, and the people who point that out aren't wrong to do so. Honestly, I think most people who say Hershey's is good would prefer Cadbury's.
You can add American's functional properties to almost any cheese with sodium citrate powder (we make and slice up baking sheets worth of "Americanized" aged cheddars, gruyere, and even blue).
I would not confuse these useful properties with goodness. Grapeseed oil is also extremely useful. But California olive oil is a better oil. American cheese is like the grapeseed of cheese.