IMHO you will change your tune with more time and experience; numerics are often more portable and unambiguous than string or serialized-object alternatives... e.g., if you pass around datetimes as "int64 count of 100-ns intervals since 1-1-1601 UTC" there is little opportunity for someone who doesn't know how to use it to get a quasi-usable yet incorrect datetime out of it.
Also note, there are plenty of database systems that either have no proper datetime datatype, or have primarily datetimes that include no TZ info.
The '100ns ticks' example is actually the Windows FILETIME, not my own invention. ISO 8601 is fine and dandy for stringified datetimes, although it's my position that strings open the door to more errors when consumed or produced by lazy/poor programmers.
Also note, there are plenty of database systems that either have no proper datetime datatype, or have primarily datetimes that include no TZ info.