IMHO, quoting in news and e-mail in general is overused because the
available options are all or nothing, and people who don't
think of bandwidth ("well sonny, back in the early 80's before you were born
I read news with a 300bps dialup...") their readers' time can't be bothered
to properly edit. As someone already noted, the threading here
is good enough that it is unusual that you even need quoting as
context is easy for the reader to find.
If I want to quote beyond the replied-to node, I simply open
another browser, cut, paste, add a couple of tags and I'm done. While this
is easy, it is some effort and makes me think twice about the
usefulness of the quote - I think the existing situation is already
optimal.
