The point of changing timezones is not to make payouts more convenient. Changing your payout time is SO easily exploitable.
As Carrie said, this is for extreme circumstances, such as I move from the US to Europe/Asia, and now my bonus energy and arena payouts are in the middle of the night.
It would be incredibly nice if arena payouts weren't smack dab in the middle of most people's busiest time of the day. However, they would have to rework the entire payout system, which I don't believe they're going to do (they don't want everyone to be able to take 1st every day).
