4 pages worth already I see. Ah well ... to answer the OP; usually yes. If the meal is better with some other starchy carb then I may have that instead. But in my day a proper meal was meat, potatoes (or a substitute) and at least a couple of other veg. And IMO a gravy or sauce so it isn't too dry.
Pie ? Well I'd not see the pastry as a substitute for the potatoes. You don't have to add potatoes obviously, but I'd usually just consider the pastry as part of the pie, and most often would want to retain the usual veg with it, including potatoes. But I guess it's personal choice. No reason to add potatoes if you didn't want to, and the quantity of food without them was sufficient.
Curry & rice ? Well in that case the rice is a substitute for the potatoes and I don't see a need to add further spuds as well. Rice or chips, normally not both at the same time. Although again it is personal choice.