That's a tough guess. Sometimes it may be smarter to use a software solution. For example if GF100 really won't have a h/w tesselator we'll see soon enough if that's true for DX11-type tesselation.
Maybe they think that for the next year nobody will really push on tessellation, or in case they can "ask" to pull it out like for dx10.1 in assassin creed, and when it will began to widespread, they'll have a new revision with hw tesselator, or so powerfull and versatile that tesselation will be a little pain compared to the other effects/poly/raytracing etc.