Comments: yes, I read Douglas Crockford's post on the matter. I guess I'm not genuinely worried about that, though, and my hope is that shipping a JS parser that works on both the client and the server will help standardize implementations from the start.

Special characters: sorry I didn't write a formal spec =), but the intent is to be a pure subset of ES5 just like regular JSON is a pure subset of ES3. Unquoted object keys in ES5 can contain only letters/numbers/_/$, and only begin with letters/_/$. So yes, '1hello' would need to be quoted, just like regular ES5.

I'm not sure how to respond to your why other than what I've already written. I never claimed this was the biggest problem we have. =)