For all those who are unhappy with WebPack, I seriously recommend brunch (http://www.brunch.io). It used to be the default that ships with Phoenix/Elixir (not sure if it still does) and it's really straightforward to get started with it.
For our app, we use Jekyll+Brunch for the static site with about, contact us, etc. And Phoenix for everything else. Brunch + VueJS is a breeze (unless you're into dynamic imports, which is required for SPAs).