One of our astute readers was just speculating in the My Sims DS comments thread about why EA didn't use Miis in My Sims, especially given that the Sims as they appear are very similar to Miis, and now we have an answer: Nintendo is being stingy! According to a quote in Next Generation from a producer at EA named Eric Chartrand, Nintendo hasn't let any of its third-party friends have development tools for integrating Miis into their software. Whether this means they haven't yet or they won't is still unknown.
Nintendo not cooperating with third parties... this sounds familiar somehow. We hope this isn't an ominous portent for the future of non-Nintendo games.
The Next-Gen article is not just about Miis, although they do figure into the whole idea about user-created avatars and content as a step into, and reaction to, the Web 2.0 participatory culture. It's a pretty good read.