It's worth noting that GW2 has a substantial amount of non-trivial in-game purchases to subsidize the persistent costs of maintaining the servers in lieu of an online fee, and some game design is specifically tailored to provide incentives for players to make these purchases.
That is a good point. I've avoided it, so I forgot that it can be a large part of the game.
However, one could argue that Maxis will likely be releasing DLC/Expansion packs for Sim City (seeing as they've done this for every other Sim game they've made) so those can be a substitute for the online fee as well. I guess time will tell.
They were planning to (there's already lots of stuff in the Collector's Edition that's also available as DLC). But they were planning to do that with Spore too, and that didn't turn out so well.
It's worth noting that GW2 has a substantial amount of non-trivial in-game purchases to subsidize the persistent costs of maintaining the servers in lieu of an online fee, and some game design is specifically tailored to provide incentives for players to make these purchases.