So something else has changed (something no one was asking for surely): now instead of the date an answer was originally posted, now you see the 'last updated' date. Sometimes, I go back to edit an old answer if I see a typo or something that I didn't catch before. That is not a significant update at all, but it still looks like I *just* posted the answer. Occasionally I will do a substantial edit or update to an answer, but then I always indicate that it's an edit/update added later.
Why not just leave the original posted date on the answer? What was wrong with that?