If you ever needed a reason to comform to some sort of standard and stick with it, I think the explanation at the beginning of this should do it. Though I suppose if you held any of my code up to this calendar that's been around thousands of years, you really can't complain about the quirks listed on that page. But there are some woofin quirks. New Year's Day has moved, whole weeks have disappeared... crazy stuff.

Some interesting history there in the Java API docs.