Not only is the cover forum largely inactive, Ooma doesn't generate much discussion in the 'main' VoIP Tech Chat forum. Since 1-Jan-2012 - topics by month:
Feb - 1 Mar - 1 Apr - 0 May - 3 Jun - 1 Jul - 2 Aug - 0 Sept - 4
There just doesn't seem to be enough to warrant a "main page forum".
There are a lot of companies that are discussed significantly more than Ooma, and don't have their own dedicated forum. Voip.ms and Callcentric come immediately to mind.
They all get discussed in the very active VoIP Tech Chat forum - where a separate posting tag for Ooma exists.