What I mean is if you remove all the fields you added (expiry date and others) which are specific to your industry, the batch number can be seen a sub-type of item. What I mean is Item "A" - Batch "B" is equivalent to a new Item "A-B".
The only difference is (I guess) you don't need to create a new Item each time a new batch comes and of course you can manage all the batches as a single object . I mean you can set/changes the GL Account prices etc, of all the batches of the same item by just modifying it once (on the item) instead of modifying all one by one if they were all distinct item.
This ability to manage "groups" of similar items is definitely lacking in FA, and is usually called (in other system) "variations".
You can have for example the same T-shirt in different colours, let's say red, blue green, in FA
you'll need either to don't track the colour in FA and create 1 T-shirt item, or create 3 differents one
Your batch modifications could be easily used to manage variations.
I use this concept of variations in my company (mainly colors).
Now, We also have concept of batch which is slightly different. Each delivery of red t-shirt come with a slightly different red.
I need to be able to track what's left for each delivery (or each batch).
I could (we the current FA) create a new item for each and have T-SHIRT Red 1, T-SHIRT Red 2 etc ...
Now,the main difference between a batch and a variation is Customers Order T-Shirt RED (ie, the order a specific variation).
However, in general they don't care of the bach (They won't order "T-Shirt Red 1" or T-Shirt Red 2"). Moreover,
they can even order before the batch exists (or the purchase order has been decided). In that case there is no way I can select the batch when I enter a customer order.
When I dispatch the good however, I'll need to specify which batch has been used. This is similar to Serial Number tracking (a serial number can be seen as a new batch for every items), the customer doesn't order a specific serial number: he order something, and get one, with a serial number.
I just wanted to clarify those points, because what you've done, I think solves a problems that other people will see as "1 dimensions variations" but not solves problems seens as "batch" or "serial number" tracking.
I'm interested in both ;-)