No, it's not relevant. If I sell a trillion dollars worth of widgets for a profit of $1M, and you sell a million dollars worth of software for a profit of $500K, how are our businesses in any way comparable?
Looking at gross revenue doesn't tell you anything. I'm not even saying Nintendo necessarily should sell their games on ios, I'm just saying that comparison is stupid. Nintendo spends a ton of money to create that $12B in revenue.
The problem with your belief is that Nintendo, like Apple, wants to control the experience they give to their consumers. Also, you are under the mistaken belief that developing games for iOS is less expensive than the other portables when it is not. iOS games feature lower development budgets because the pricing model cannot support higher budgets. The risk is too great for a AAA budget when the store hasn't shown it can support games priced high enough to support the budget. Nintendo has the highest margins on their own platform and they control the experience top to bottom. If they had to deal with Apple who gives to shits about games, they couldn't control what is in the new hardware, software and everything.
If Nintendo were to develop a mainline Pokemon game for iOS the cost would be the same as if it were developed on the DS. The number of people working on the game wouldn't change. They would still need the artists, engineers, programers, designers, testers, etc but the price of which they can charge would drop from $40 to about $10. For people who are on the iOS train, call me when a game releases in the App Store for $40 and is a big hit, doesn't drop in price, and continues to sell for YEARS after its initial release.