Starving a realm, in most cases, is next to impossible unless they managed themselves really bad.
Also, you need to remember that the less damaging wars become, the less people will be motivated to initiate wars, and those initiated will more likely result in total destruction in order to prevent quick repair.
It's not that I want regions to take forever to recover, but rather that I want wars to matter.
And you don't need all of your cities to be at 100% production to be able to engage in warfare. Finally, if cities recovered too quickly, it'd be too easy to implode due to food demand growing faster than food production, as was seen in Darfix twice I believe.
