It's not a secret that we promote Typescript as the first choice for Angular2 - this is a conscious decision based on both technical reasoning as well as feedback from our developer community.
I can count on one hand the number of teams I've spoken to who really want to use ES6 - the vast majority are happy using Typescript.
Typescript also allows us to do the kind of static analysis we use to do ahead-of-time template compilation, something that is significantly more difficult with ES5/6 - we've discussed making this work in the future, but for now it's a lot of engineering investment for something there just isn't the demand for.
A couple of other things I want to mention - "enterprise" gets thrown around on HN sometimes as a bit of a dirty word. We don't see it like that at all - the vast majority of Angular 1 users are exactly enterprise, and we're solving for the problems that large teams like them run into.
Now we're released and stable, I think it's a reasonable ask to add some specific docs on ES6 usage (or at least where it differs from TS), I'll bring it up at the next docs meeting.
Anecdotally, my experience talking to outside teams tells me that TS is not the complexity problem people have - the vast majority of devs coming from ES5-land have trouble with ES modules and bundling, rather than the specifics of ES/TS itself - this is part of the reason we're working hard on the angular-CLI.
As far as Google/Angular's commitment to the outside world - we have a Developer Relations team (of which I'm at member) - our only job is making non-Google developers successful with Angular. Feel free to reach out to me (@robwormald) or @stephenfluin if you've got questions or concerns. We both come from "enterprise" webdev and a big part of our job is making sure outside developers are represented in eng-team decision making.
Also reach out if this is something you care about deeply and want to contribute to the documentation - we'd love your help and I'll put you in touch with the right people.