First off, I think far too many people are far too focused on the technology behind these solutions; and have an odd belief that one of the main console manufacturers couldn't produce the same technology that the other console manufacturers could. The truth is that the specific technology doesn't matter to consumers (that much), and all of the console manufacturers have the resources and relationships to implement anything the other manufacturers can produce.
The reason why Sony and Nintendo passed up on Kinect was (probably) a business decision. It could have been based on the cost being too high for an implementation that met people's expectations, or that controller free gaming had been less than successful when it has been tried in the past, or their HCI R&D is moving in a direction which didn't see value in Kinect. The decision they made might be right, or it could be wrong, or it might be more mixed; and it is entirely possible that it could seem wrong initially and then down the road seem like the correct decision.