The teams of people want to get their work out into the public to make a big splash so they can get a sweet bonus before anyone realizes that it's not actually useful or effective. See also: Google Wave, and 80% of their other products.

They don't get a sweet bonus and promotion for helping another team improve a product, so why collaborate? Just create your own chat app according to your own team's vision/goals/available technology and release it and hope it gains more traction than the other teams' existing options.