What net savings? Dates will still get padded out to a byte alignment when in memory and being processed on the CPU (or gods help us all). You'd just be making

What net savings? Dates will still get padded out to a byte alignment when in memory and being processed on the CPU (or gods help us all). You'd just be making it so there's extra handling any time you serialized it across I/O, to save a few bytes there. If you really wanted to save those bytes you can write your own serialization format, and that might make sense if you're sending massive amounts of timestamps or similar (but you'd probably see better results by compressing it first), but don't try and rope the rest of us into that pain when we aren't, like, serializing logs or something.