WoW has similarly minor downtime most weeks, but the point still stands: MMO players are willing to tolerate significantly longer and more frequent interruptions due to the nature of the games and the architecture necessary to support them.

I don't know how much simulation is being done server-side or how resource intensive it is, but if the Sim City of 10+ years ago was possible without it, I'm pretty sure EA could've done this one without it as well. Smells like an excuse to me.