I agree that it would always be better to improve the AI than to change some great game-element so that the AI has less problems with it. But I don't consider the wasting of shields and food a great game element (this is personal I admit) so if the change to shields and food cascade improves the AI, then that is an added beneficial side-effect for me.
As for improving the AI: I'm not an expert in AI-programming, but as far as I know this is far more difficult than people believe it is. There is a big difference between being able to explain to a friend how to micromanage and telling a computerprogram how to micromanage. You'll have to write very general routines that always do the right kind of micromanagement. I think this is very difficult. Determining what is the right level of production is pretty difficult for a computer.
An example: We have a city in the late middle ages (musketmen and knights are around). Good cities in this era have a productionlevel of around 20 and so does our city. The city has no hills and the only way to micromanage it is by choosing between building mines or irrigation. To produce knights a production level of 18 would be ok (4* 18 =72, minimal loss), to produce musketmen a production level of 20 would be perfect (3*20= 60, no loss). So the AI has to decide somehow what unit is needed more. This is a very vague decision and thus difficult for the AI to make. Say it chooses for knights because it wants to start a war (AI's never plan things but this is a theoretical super-AI). It builds the mines and irrigation in such a way that a production level of 18 is reached. Now it is attacked by another AI and some of its musketmen are killed. Some routine tells it, it needs musketman, so the just changed terrainimprovements are changed back so that a production level of 20 is reached. By the time the terrainimprovements are changed the weak attacking AI forces are already beaten and the AI wants to build knights again to take some cities of this AI opponent.
You see where I'm going...

A lot of wasted workeractions. This is just an example and in reality the AI has much more difficulty deciding if musketmen or knights are needed and other buildings and units have to be considered also. And this has to be done for each time-period and cross-linked with all kinds of strategies. And the workers have to be present at the right spots on the map to do this micromanagement.
One of the biggest problems with the AI and micromanagement is that the AI doesn't think about the big picture or about what will be happening in 10 turns and that is important for some kinds of micromanagement.
The level of micromanagement that I'm using to defeat the AI is unattainable for an AI, I think. That's another reason for me to vote yes for this change, although not the most important one. That would be that I don't really like this kind of unintelligent micromanagement.
If it were easy to learn micromangement to the AI then Soren would have done it. Maybe some level of micromanagement is attainable for the AI (change between mined hill and irrigated grasland when beneficial, although the term beneficial is not that easy to define). But as I said before I don't know that much about AI-programming so even this might be too difficult.