Automatic download of content into the newsletter
The main benefit is massive time savings when wanting to showcase multiple items in your newsletter. Think promotional products, or new products being introduced.
When working with a fully-branded, custom, modular template - usually the product names, descriptions, links, and images need to be replaced. Usually this is done manually - either directly in HTML, or in some kind of WYSIWYG drag and drop editor.
With generator this work can be greatly optimized. Point to a product page with a URL, and get all the data you want to be put into the newsletter.
Best use case: e-commerce businesses and email marketing agencies, showcasing products in their newsletters. Newsletters aggregating articles from blogs or news websites.