Attachments are different than product images added through the product edit form, correct? Aren't the images stored as base64 strings in the product_template table?

That's what I'm thinking as well: attachments (documents) are stored on the file system with module Document Management or something similar. Product pictures seem to be stored in the database as base64 without alternative. Which makes my point: when you work with 4000+ products and a collection that changes every year, the database size gets enormous without much added value.