I'm not sure if we need a forum for evangelism -- but it can't hurt...
It very well CAN hurt. A forum created before there is insufficient activity to justify it will actually DECREASE discussion in that area, because users go there and, seeing no posts, think, "Huh, I guess nobody is interested in this after all. Never mind." I've seen this happen many, many times.
The existence of these forums has been debated long enough; it's time to take action, and then fix whatever problems might occur as a result.
Funny, I've always been a fan of, "If it ain't broke, ..."