Not in my campaign where half of my territory hasn't been touched in years simply because they are too far away from the front lines. And no we don't need even longer sieges, they already take long enough.
Well that's fine then. It means you're doing a good job protecting your fiefs. Why should they now start to starve?
Are you suggesting that players ought to be punished for taking care of their fiefs? That's absurd.
I'll stand by this axiom - a prosperous city ought never to starve in peacetime. If not via orchards and villages then by increased grain shipments.
What is also true however, is that as a city approaches infinite prosperity, the ability to support the city's consumption purely from granaries must proportionally decrease i.e. making it far easier for a prosperous city to slip into starvation during wartime/sieges.
Now this would be a good time for TW to introduce grain related quests that would reward the player with City loyalty and alleviate starvation for a short period of time.