Agreeing with comments made by MS executives previously, Suda 51 indicates that third party titles for the Wii aren't selling in Japan and Nintendo are the only ones who really profit from the Wii. Speaking specifically about No More Heroes, Suda commented that sales weren't as high as he'd hoped and Nintendo titles are doing well but this pattern expands beyond Japan too.
Goichi Suda, otherwise known as Suda 51, claims that third-party titles for the Wii aren't selling in Japan and that only Nintendo is really profiting from its success.News Source: Gamesradar
Speaking about Japanese sales of his game, No More Heroes, he says, "Whilst the sales weren't as high as I hoped, other titles for Wii aren't selling so well either. Only Nintendo titles are doing well. This isn't just because of the current situation in Japan, as this is happening outside Japan."
He also expressed surprise over the casual audience that has been the primary adopters of the Wii. "Actually I was very surprised about the reality about Wii, because before I was making this game, I wasn't expecting that Wii would be a console targeted only for non-gamers. I expected more games for hardcore gamers. The reality is different to what I expected."
The best selling Wii games are the Wii exclusives, so Nintendo should focus on that.