Raising Cane's anyone? (do one thing do it well)
-They have Chicken fingers and .. Chicken fingers... and more chicken fingers.
I fully agree with your point and believe most fast food places should go back to their roots by having a smaller core menu and doing that very well instead of posting a menu board with dozens and dozens of items of lesser quality.
I think, however, the rapid proliferation of formerly regional chains has also hurt their quality. You mentioned Cane's. I was stationed in Bossier City in the early 2000s when we came across Cane's for the first time. It was refreshingly new to us and had lots of Louisiana charm. The "Caniac Combo" was too big to finish. Now, with Cane's everywhere, there's virtually no charm and the big combo is more like six nuggets. We now prefer Zaxby's.
Also back in the early 2000s there was this place in the DC area called Five Guys. It was a real treat when we were in the area. And like a shotgun blast, this chain exploded across the national landscape. What was once unique and tasty is now overpriced and greasy.
Ditto Culvers. I grew up in Wisconsin and remember how unique their custard and butterburgers were. Now they have a huge menu, small sizes, high prices, and long waits...mostly sans the famous Wisconsin hospitality.
Hell, in the 1970s even Wendy's was quite regional. First saw one when we moved to Columbus in 1977. Had the entire menu on a board next to the cashier: Single, Double, Triple, fries, drinks and Frosties. Cheese and tomato 10 cents extra. By the time you finished paying your food was on the tray and you were on your way. Now you get a number and have to sit & wait...for a less-than-stellar burger and cold fries.
Simplifying menus would be great, but there was always something about the unique local/regional nature of fast food places in the old days.