Annual Power downs are not unusual and not just a JP thing, you'll find that this happens in a lot of places. Certainly in the UK buildings have to be powered down for maintenance at least once a year to maintain services that run 24/7 and to test backup power generators/UPS systems to ensure they will continue to work if there ever was an unintentional power outage.

It's all tied in with business continuity and risk management, but most people don't know it happens because it usually gets done on weekends or times least disruptive to a business - in the case of an MMO there is no time during the day where it will go unnoticed.