This is infrastructure maintenance. Meaning they are working on the physical hardware of the game. Likely cleaning and replacing servers. Do you complain because you had to turn off your computer to hit it with a blast of canned air? Same difference only those computers likely take up entire floors. It's going to take a while.

Also emergency maintenance is just that, emergency. There's a problem that has to be fixed and can't wait.

On the whole, this game has less downtime than WoW. In between major patches we have one maintenance a month. ONE! WoW has theirs once a week. Which would you prefer? One slightly longer maintenance a month? Or 4 to 5 shorter ones a month?