I spoke with Will why he has used the data module to define the product category hierarchy instead of using a "Product Category" page template to do so. The reason why is that he wanted to be able to have localized URL's for SEO reasons. In other words, this is a workaround, nothing more, and makes understanding and using the shop module unnecessarily complicated.

Please define a page template "Product Category" and ensure this works the same way like now to support localization. In other words, if the page is served for German, the URL should contain the German category (== Page Title) (currently in addition to the English one but I think we could drop the English one in that case)

If so, this would solve a lot of issues at once:

1. it would be much more intuitive to create the product category hierarchy
2. it would allow us to use standard pages & their functionality for instance to have a header per product category
3. it would reduce the complexity of the shop configuration interface (because the categories move out of the data module)
4. it would make it clear what product categories actually are (i.e. that they define the page hierarchy)

Once implemented, drop the Product Categorization scheme we currently use as it would not be needed anymore. Update the product category selection dialog for the products to use this page structure instead.