++1 for this feature!
example: We create promotional displays for our dealers that are built from 10-15 product variants. It takes time to build these displays so we need to build them, and stock them in our warehouse.
Advantage of Composite: Promo-Displays change and differ over time and it is really nice being able to track and see what/which displays each dealer has on hand, helping alert us if a dealer needs an updated display.
Problem with Current Composite: With no option to commit product variant stock to the component, the inventory of the products in the displays shows in general inventory, miss-representing what is actually in stock for sale, upsetting purchase order planning.
Possible Solution: Add option check box to commit products within a composite variant. Adding a composite variant to inventory with the option checked pulls the products within the composite as committed.