Well, as some fellow forumers pointed out already, the 14+4CUs might be an incorrect assumption because it would make no sense to have 4 CUs in store when they could be used freely.Mandatory Kinect for XBXOne could mean the diffusion of some of its functions for PSEye in multiplat games. Mainly voice recognition, because PSEye and Kinect2 are 2 completely different beasts.
COD Ghost, a multiplat game, x example, is rumored to have the dog controlled via voice commands.
But everything depend on Sony!
Speech recognition on XBO is managed via a dedicated chip and it is completely free, i.e. no impact on GPU or CPU cores.
I suppose that the PSEye will not have this kind of chip, and, because PSEye is completely optional in the PS4 ecosystem, it is safe to assume that PS4 will not feature this kind of dedicated chip on board.
If I remember correctly, speech recognition was quite an heavy task for the first kinect.
Maybe this could mean, translated on PS4 environment, that 1CU of the 4 extra CUs could be reserved for speech recognition tasks in multiplatform games.
But in order to work, this is something that Sony must decide from the beginning.
For all the multiplat games that support Voice Commands 1 CU should be reserved for this task no matter if you have PsEye or not, no matter if you will use this feature or not.
And so, as I have said in the "VS Audio" discussion, I have strong feeling that the "14CU+ 4CU rule" is coded and already established by Sony, at least for the 3d party developers.
And speaking of this, DF some times ago received confirmation from a developers that Sony mandate some kind of reservation for remote play or camera implementation.
Other than that, I agree with you, and I think that the OP has an excellent point, because I had never thought of it, but the universal use of Kinect could also help developers to implement certain mechanics if you have the PSEye, provided the development tools are great.
Iirc, adding voice commands for Kinect in any game is so easy, it takes 5 minutes to implement, if not less --because of the development tools.