Issue #1: if you have an out of stock item, then change the inventory count, but forget to update the option count, potential buyers are notified, but find the item still out of stock (all options show 0 in stock).
Why It Matters: This has lost some sales along the way -- in my store a couple of times and for other sellers (from my observation as a buyer).
Requirement: prevent this gotcha, but let's not lose or fundamentally alter how options are handled.
Suggestion: The main inventory # is superfluous and error prone for items with options, so eliminate it. HOWEVER...
There are two flavors of options-- variants and add-ons. I sell, e.g., the ATtiny84 prototyping board in variants (no crystal, 8MHz, 16MHz). The total # of ATtiny84 prototyping boards in stock is the total of -- only -- the variants in stock. I offer ATtiny84A chips as add-ons and those inventories are independent of the board/product inventory. One might be out of stock without affecting the other.
So ideally it'd be nice to have single entry-point for managing inventory counts for variants and thus total # of product in stock. The current mechanism seems reasonably suited to managing add-ons, instead.