My guess is that knowing vB, in one of their million pages in the control panel, there's some easy way to select a different image to use for xyz (In this case replied threads).
Now, Mr. Brandon seems pretty busy. BUT.. if someone cared enough, took the time to change the image so that it had a dot, had it look nice, and submitted it to Brandon, the odds are that he might be able to do a good ole switch-er-ru. Of course, it's all up to him, and he very well might not, but I'd guess if he has a little gif file sittin right there that looks cool, he'd just upload and click the one little button to change it.
Heh.. sorry, I honestly don't have enough time to take it into Photoshop, but for someone who's passionate about having the dot back, they might
~ Jack