(((interference)))
Veteran
It's a cost reduction measure for the long term. It is what allows MS to use DDR3 for main memory. Three years from now MS is going use a half width DDR4 interface on XBox One V1.1, while Sony will be stuck with boutique GDDR5 for the duration.
Cheers
Yup, definitely cost related - the engineers came up with it as a way of having 8GB of memory while maintaining adequate performance - without breaking the bank on GDDR5 that is.