Maxis apparently really wants people to mod SimCity, according to a recent blog post encouraging the modding community to grow. When I think of SimCity, I rarely think of freedom and creativity, with its weird limitations and restrictions, but that doesn't mean modders have to be so restricted.
I'm joking, of course, because Maxis has a bunch of caveats for modders, a list of rules, which they hope will ensure "the safety and integrity of the SimCity experience". The sound you're hearing is my head smashing through my desk and sending my mouse, selection of brightly-coloured pens and slighty-too-full ashtray flying across the room.
An always-online experience is far from conducive to the thowing caution to the wind, experimental approach to mods that tend to result in truly creative creations, and it doesn't look like Maxis has been able to reconcile this at all. In fact, the first rule states that you can't do anything that will affect the simulation for multiplayer games, which of course doesn't make much sense when the single-player and multiplayer experience is inextricably linked, meaning that you can't really do anything that would affect the single-player game either.
Fiddling with any ".com, .exe, .dll, .so or other executable files" is also strictly forbidden, and every mod must adhere to the age rating system that SimCity falls under depending on what country you're playing in, which essentially means you're not allowed to create anything that might not be appropriate for a young child.
There are a lot of extra rules, and Maxis will take down any offending mods, revoke permissions and discipline naughty players if their creations threaten the integrity of the game or stop other players from having "the best possible gaming experience," which is obviously open to interpretation.
What we're left with are some tame visual mods, which is hardly the sort of mod support one would hope from for a series that was once known for encouraging creation and creativity. But that's not what SimCity is about, now; it's a social game for people to make wee towns to share with their friends or total strangers.
I pretty much hit the limit of what I could do with SimCity in a weekend, compared to the years I spent playing SimCity 4, but mods could certainly give it the shot in the arm it so sorely needs, but lamentably it seems that Maxis are not willing to give modders the space to actually do very much.