I constantly find my posts on that forum either have little criticism or none at all before they completely disappear to the depths of the forum, covered by so many others. Critiques from chats aren't always as helpful as forum posts. A second draft critique forum would be pretty nice just for another way to get feedback.
While the forums can bury posts, there are alternate methods. One such method is to PM a member of the Forum Crit Team. Another is to ask for a chat reviewer to leave a review in the thread rather than fire it at you in chat.
Hope this helps.
Do you mean a forum for second drafts or just a second forum for drafts?
Either way, the problem is that just because there are two forums, the number of people doing critique isn't going to magically double. I'm also sure that a lot of people would start posting the same drafts in both, which would lead to feedback getting split up and actually make your post less likely to be seen.