I'm not convinced at all that data-size is the reason for any of this. You would also be sending more data on any type that is not a primitive, i.e. any type t

I'm not convinced at all that data-size is the reason for any of this. You would also be sending more data on any type that is not a primitive, i.e. any type that is bigger then the sentinel null value, you would have to send the full blown struct.