Order the Term selection field as a hierarchical multi select instead of a flat list.

It s a simple patch to reuse taxonomy_form_all() to generate a standard "select your terms" list:

Term A
-Sub Term A
Term B

This replaces the kludgy "select your unhierarchical terms from a sea of terms:
Term A
Sub Term A
Term B

This is especially useful when your catalog has alot of "Accessory" categories, etc.