I'm on the Babel team and this decision was intentional. The purpose that Babel serves now is more geared towards providing the building blocks to create a Java

I'm on the Babel team and this decision was intentional. The purpose that Babel serves now is more geared towards providing the building blocks to create a JavaScript development experience rather than providing one. It's up to Ember, React, React Native, or your favorite boilerplate, cli, etc to create that nice getting started experience with healthy defaults. We either do a shitty job trying to serve everyone and everything or we take a step back and enable people more knowledgeable with their user needs to create those experiences. Babel < 6 was trying to be everything for everyone and that wasn't working out. Everyone wanted to get their pet feature in. And we came under fire for making it easy for people to use experimental features. That said, there is probably room to create a es2015-cli or something like it that provides a default experience, but that's orthogonal to this discussion. Finally, the point you raise about Babel just disappearing into the stack is also misinformed. Transpiling should always be a technical decision to be made. For example, you should know that a for-of statement will transpile to include a bunch of runtime checks that would be slow in hot code etc.