When using Webpack, it makes complete sense to use it to package your client-side JS. But what is the purpose of using it to compile your SASS and load your CSS into your page? In the end it appears that you need to use another Webpack plugin (ExtractTextWebpackPlugin) in order to pull out the CSS when you are ready to deploy to production.
It seems like you are going full circle here. Before Webpack you load your CSS in the <head> using a <link> tag like normal. Now using Webpack you load it via your JS bundle. And now for production you use a Webpack plugin to put it right back into the <head> tag again. So what's the point?
There are already dozens of tools and methods for compiling your CSS and live-reloading it in the page without Webpack. What is the advantage of using Webpack for your SASS/LESS/CSS to begin with?