Why is the author's opinion more relevant or acceptable than the submitter's or HN's? You state it like it's obvious, but I don't see why the author's opinion is particularly special.
The way I see it, when I click a link, I'm signalling that I'm interested in reading the author's opinion, not the submitter's interpretation of the subject - that's what the comment section is for.
When I put it that way, it only makes sense that the title should reflect the original article's title.
When I'm reading through a list of titles on HN deciding which to click on, I'm more interested in why the submitter thinks it's relevant to HN and why they think I should click it. If I do click through, I will read the title.
When I put it that way, it only makes sense that the title should reflect the original article's title.