When it is being sold as the integration point for Vault, the Item Master is inadequate.
First, lifecycles for items should be as configurable as for files. If you use the system as intended and control the lifecycle of the file through the item, you are severely constricted.
Items should assume the properties of the files that created them, or they should be easily called through the API.
Given the possibility that an item could be created before the CAD representation exists, there needs to be an ability to attach a CAD file as a representation of an item after the item has been created (this is also a huge hurdle if a company converts a product from 2D to 3D).
Document item types should exist so that external applications can reference and control files that don't represent parts.
OR do away with the item master and integrate the BOM capabilities (for 2D and 3D) of item master into the file interface and do away with item master altogether.
This would probably help with any plm integration, PLM360 included.