Last May we were on an American Queen Mississippi River trip. There were no speciality restaurants, just a small buffet and main dining. The buffet did have prime rib nightly, but perhaps only eight to 10 selections in total. (Two proteins, two carbs, two veggies, etc) That's all. We did main dining five nights and had second seating. Portions were very small. One night they ran out of baked potatoes! How could that happen on a cruise? And twice during the week the preferred dessert selections were gone by the time we tried to order.
I agree that food quality has gone downhill - our two most recent cruises were on Celebrity as is an upcoming one -- but at least there is still a wide selection on mass market cruise lines.