Well, I'm all for waste not, want not, but not on Thanksgiving. It's a food holiday, so the idea would presumably be to serve the best food you can afford on a day like that?
FWIW, my parents were immigrants, and when my Dad was still alive we never had a casserole of any type on the extended family holiday table. (Lots of root veggies, yes, because it was winter after all, and most green stuff was prohibitively expensive at that time of year.) My mother's signature company dish was cauliflower with bechamel sauce, and we always had mashed potatoes, but that was where it ended. No syrup yams, no cranberry gel, no pumpkin pie. There was usually a dish of pickled beets and some peas, and dessert was fruitcake or cheese if you didn't want sweets. The American stuff started creeping in when my oldest sister married, and after Dad died and Mom delegated more it really took off ... and I ate yet more turkey.
There are certain mushy things that I will make because my DH grew up with them, but those are for him, so if we're not doing the extended family there are just some herbed, sauteed or roasted veggies on the table with maybe a bit of butter on them. I grew up with potatoes at every meal except breakfast, so I make special mash for this holiday, but my one imperative for those is to keep them HOT -- I always hated it them served cold, and it always happened quickly because my mother had a habit of adding cold milk to them. I leave the butter at room temp for several hours first and heat the cream before adding it. (Though I don't add much. IMO "whipping" mashed potatoes absolutely ruins them. In my house you mash by hand or we don't serve it.)