I think this is by design as the threads list, “What’s New” widget (not a good name choice in this situation), shows only the original name of a thread and the author of the thread. As opposed to the older version, when it was showing “Re: name of the thread” and the author of the last reply in the list. As it shows the original message, it goes to that original message. Not sure though that in the old version it was the default behavior. I was using a custom view with Recent Content widget i think. Not a fan of a new way, as i don’t see who has replied last on the thread at the glance. Usually that was enough to see if there is a new post (especially if i saw my own avatar as a last poster).
Though, i was using a flat view with pages (15 per page) and if there were more than 15 posts it was always going to the first page