Even pedantically, that's not true: the HN guidelines have never said you must always use the original title. Pedantry aside, the important thing above is language in the article itself that is representative of what it says. That's both why we changed the title and what we changed it to.
> allow both titles and descriptions on posts with URLs.
I appreciate the suggestion, but we're unlikely to do that. On HN, submitting a story conveys no special rights, and submitters do not get to frame the story for everybody else. Framing it for everybody else effectively means controlling the discussion. We want discussion to be driven by the article itself, not a single user's spin. If a submitter wishes to offer a description or say what they think is important about a story, they're welcome to do so by adding a comment to the thread on the same footing as everybody else.