Mary, I really don't believe there's anything that the Multihull Council and the Multihull committee can't do. All it takes, as I believe you are learning with NAMSA, and as Mark Schneider said, "that would take participation and work on our part to effect such an agenda."
The limiting factor is the lack of volunteers/workers. US Sailing doesn't have extra money and extra workers just laying around. However they already have the organizational framework in place.
The work of both the Multihull Council and Multihull Committee is, I believe, privately funded, just like NAMSA. The advantage is we don't have to re-invent the organization. Take the efforts that are going to building NAMSA and instead direct them to improving and directing US Sailing.
It would be far easier to work in the existing framework, and to direct money and volunteers there, bringing our agenda with them, to participate in and help shape the direction of US Sailing, then it will be to create a new organization to do the same thing.