Why don't you support Flow anymore?

It is just buggy. We had a lot of issues with it. You can still use (old) version of this template with flow: here is the last release.
I wrote an article about this, check it out.

Why Nuxt?

Nuxt offers a thin abstraction layer for ssr and building your project. We have struggled with ssr for long enough, and we don't want to go back.
Also, Nuxt's predefined build configuration suits us very well. Wide choice of plugins also allows solving problems faster.

Do you support Prettier?

Nope. And we never will.
We strongly believe that writing good and well-formated code is a developer's responsibility.
We also have strong linting rules and CI step. So any improperly formatted code won't make its way into the build.
We also do not encourage using eslint --fix.

Why do you use heroku for a demo project?

This allows us to show how easy it is to deploy a full-featured isomorphic app. The main idea of this example is to demonstrate server-side rendering features. Both with basic client interactions.

Why do you use vscode and not vim/sublime/emacs/webstorm?

First of all, you don't have to use vscode. Use the editor you love. Secondly, vscode is free (as in freedom), actively supported, has a lot of js plugins.
That's why we recommend it.