I am pretty excited for this release. I worked a bit with ZURB Foundation for Email 1 (Ink) and you still had to deal with this terrible table structure that reminds me of 1990's HTML. I think there are some really good ideas here, most importantly an abstraction that allows you to quickly develop branded and responsive HTML emails using some simple html structure that masks a lot of having to deal with those tables, TDs, etc.
Awesome job on the ZURB Foundation 6 launch. Great graphics, sci-fi theme, some awesome new features for the framework. The flexbox grid, yeti launch and the new menu component are worth looking at.
I'd love to use static site generators for my client work but they usually ask for features like e-commerce that completely rule out it's use.
Usability is also an issue. Wordpress is a far more friendly environment for them to make changes or create a new post than creating a text file with specific formatting and running a script.
There are services such as snipcart and foxycart that you can trigger via html and javascript. Like most non-locally hosted ecommerce solutions they send you to a subdomain for the final checkout. I have tested both on a static site and both work very well. Snipcart is easier to implement but lacks customization. If you are looking for heavy customization (like custom products beyond just sizes, colors and options) without having to build out your own system, check out foxycart.