If you've ever moved country, and imported some data from the old country and mixed it with data from your new country, it quickly becomes obvious why preservin

If you've ever moved country, and imported some data from the old country and mixed it with data from your new country, it quickly becomes obvious why preserving source timezone is a deeply useful attribute ("It's a beautifully sunny day! -- me, 04:17hrs"). Or at the very least, preserving the time offset.