Nintendo console attachment rates are horrendously low, the Wii's was something like 1:1 which is just ridiculous, while the 3DS and even DS had pretty abysmal attachment rates too. So yeah if you are a publisher why would you even bother throwing money and putting effort into a multiplatform Nintendo system game when you know it will more than likely just not sell at all and is guaranteed to sell better on any other system.
Myth.
At launch, the Wii had an attach-rate of 2 versus an attach-rate of 3.69 for the Xbox 360 and 1.09 for the PS3. It even featured a couple third-party successes such as Red Steel selling over a million worldwide and Call of Duty 3 selling a respectable amount.
Let's look at the first 20 months of the Wii.
The Wii was able to sell 33 million units of third-party games versus 29 million for the 360 and 20 million for the PS3. Contrary to popular belief, third-party software did sell on the Wii, even more than it did on the HD counterparts.
Fast-forward to December 2007 and you'll see that the
Wii still has a respectable attach-rate at 8.11 versus 5.04 and 7.67 on the PS3 and 360. There were also numerous third-party games that sold well like Call of Duty: WAR at over a million, Resident Evil: Umbrella Chronicles at 1.2 million, Resident Evil 4 at 1.9 million and Guitar Hero III at 2 million.
And now (March 2011), the Wii still features a comparable LTD attach-rate to the 360 and PS3 as shown in the image above.
Third-party games can sell on Nintendo systems. It just requires a little common-sense on the part of the publisher. Releasing a one-year old full-priced port of a single entry into a series that's getting a trilogy release on other platforms (Mass Effect 3) is one way to ensure that your game sells like shit. Releasing your game with absolutely no advertising for the Wii U version is another way to ensure your game sells like shit. Releasing a multiplatform game
at a higher price for the Wii U version is yet another way to ensure your game doesn't sell.
The only pub that seems to be doing anything right is Ubisoft by cultivating a core userbase with games such as Assassin's Creed 3 and ZombiU ensuring future successes (well that remains to be seen) with later games that they release (Assassin's Creed IV, Watch Dogs).