I don't think they're going for profitability. There's no ads in Miitomo, nor is there a real (read: fake) sense of progression trying to hook in those with compulsive personalities. They're not going to devalue the brand like that, it seems. Instead they start off by literally paying the player for continuing to play.
This app has exactly three purposes: To kickstart My Nintendo in a meaningful way (it has); to draw brand confidence in Nintendo on mobile (it has, due to the genuine avoidance of scammy mobile practices and encouragement); and to boost visibility for non-users (it has, more on that in a sec).
Miitomo is a meme machine. I've seen it all over reddit, trending on Twitter, and on a bunch of sites that don't cover gaming often. It doesn't matter how much they make off microtransactions, because this app has gone viral in probably exactly the way they'd hoped.
You should check out my YouTube channel, The Golden Bolt! I review all types of video games, both classic and modern, and I also give short flyover reviews of the free games each month on PlayStation Plus to tell you if they're worth downloading. After all, the games may be free, but your time is valuable!
