Agree with the 1 forum with platform specific subforums. But there’s no reason to release the PC version later if time is managed correctly. They just need to make sure they have people working on the platform specific interfaces when it’s appropriate. Games like Deus Ex managed to release across all 3 platforms at the same time with a tailored PC interface (and they were just as “under the gun” to release).
It doesn’t take much to make the interface “right” for the PC. Unfortunately nowadays even that small effort is often overlooked. At least a lot of games are happy to leave the modding community to tweak things. Brink, unfortunately, wasn’t and they didn’t leave much tweaking possibilities at all.
They should use the PC as a testing ground for ideas and tweaks, but also realise that certain things are unique to the platform. Holding off patches until all platforms are ready only makes everyone unhappy. Content releases: fine, I guess. Release all 3 at the same time. Patch releases: when it’s ready let them have it!