[Xk]

The current implementation uses an iframe and so they can't read the data out of the iframe (same-origin policy).

This would require injecting javascript on to news.ycombinator.com. It wouldn't be so bad, but it would require user interaction to do that. If it requires user interaction then it'll be less used.

Granted, they could make an extension which does that -- but now you have to download something just to use chat. That's a big barrier to entry.