If I share an HN link among my Facebook friends, as I sometimes do, a snippet of the discussion is shown, and that (besides my tagline to the submitted link) lets people know what to expect. If I share a link in an email, I generally introduce it to the recipients. What is the use case for changing the link structure of Hacker News? I'm not sure that "immediately clear" is guaranteed by all of the user-submitted titles here, for example.
Also, this would make it much easier to decipher the links I have sprinkled through various notes in Evernote.
Ironically, I find this would be most useful when including links to previous HN discussions on Hacker News itself, because this is one of the few sites that doesn't let you put in human-readable text for the links you include.
javascript:history.pushState({}, document.title, document.URL + "&title=" + document.querySelector('.title a').innerText.toLowerCase().replace(/[^\w ]+/g,'').replace(/ +/g,'-'))