You get significantly more than transmitting a number. - You get automatic conversion to/from a known datatype, Timestamp, not to an arbitrary number - You ge

You get significantly more than transmitting a number. - You get automatic conversion to/from a known datatype, Timestamp, not to an arbitrary number - You get automatic checks on the validity of this datatype - You can specify exact precision of this datatype (for example, you may want to represent nanoseconds, not milliseconds, since epoch)