Of course this isn't really a new issue - it's the same in XF 1.5. Arguably not an issue at all, because the logic of the inconsistency is that profile posts have inline moderation and that can be used to undelete. By contrast, profile post comments do not support inline moderation and therefore that needs a specific controller action to do it.
It's not unique either. Notably posts is exactly the same.
That said, as per the above, we have made some changes here. We've actually added a new Undelete controller plugin which is similar to the Delete plugin we added in XF 2.1.
Makes things slightly easier so there isn't technically an excuse anymore for not having a dedicated undelete action, I guess!