I agree with Argel, it does make sense to have those links for posts with no replies yet. With that being said it seems that having a difference in the display for posts which have replies and those without replies will lead to wasted space on the majority of content on the site. The only idea I have is to make the "0 direct replies" link direct traffic to the reply page, or move the "offer your reply" link next to the "0 direct replies" link.