I was thinking about this the other day. Part of the food/gold situation now is good - it creates conflict (huzzah). But it also eats up a lot of time (boo).
One nice thing about the old system was that you could dedicate one or more regions' surpluses to a particular place; 'this rural feeds this city.' But this didn't create any conflict.
Historically, medieval lords were not concerned with day-to-day movements of bushels of food. Their stewards might be aware of it but they'd only be concerned if they were saving up for a siege, since it was sieges and long winters that granaries were for. Starving during the summer or autumn was unusual, though not unheard of.
Sieges were a huge part of medieval war but they aren't represented in BM. For so long as that's true, it doesn't make any sense to build a food system around just winter and sieges. But in the long run, it might be beneficial to consider an alternative to the 'everybody rushes the walls on the first day' such that a) lords are really only concerned with emergency stores, not day-to-day stores, and b) those emergency stores are really important.
