It shouldn't be a regular thing but if you started playing in one time zone or country and at some point moved to another country which is 9+ hours different than where you started, I don't see it being an issue for a one time change.
I completely agree with not having a mechanic in place where people can change it on their own, that would cause problems as listed above but if it's a 1-2 per year option where you have to go through customer service (military being deployed overseas and stuff) I have no problem with it