They are generally afraid to compete with Nintendo.

Madworld and No More Heroes were not expensive games.

Two main reasons regarding Wii

1) Many developers either do not understand or simply don't relate to the Wii audience. For many working on Wii is working outside of their comfort zone.

2) Most of the industry is inbred. People who grew up playing games and now want to make those same games but bigger, better, badder. They want to make graphically beautiful games with lots of violence and that works and sells best on HD consoles. They do not want to make Petz, Imaginez, Brain Ages, Sport Active or other such titles.

They didn´t seem to be in the NES and SNES generations.

Indeed.

Wii audience is unpredictable in term of buying intention outside of very casual titles and Nintendo titles...

Heck I'm not the one saying it, Iwata called the casual Wii customers 'fickle'...........

It's not an excuse. They literally have to make an entirely different game for the Wii. In doing that it's a lot more than say porting it between PS3, 360, and PC which can all be worked on as "one". Thus they have to weigh in the risks of putting such and such game on the Wii and whether or not it will contribute greatly enough to overall profit and revenue.

However, they also have to consider whether or not if they do a Wii version to not make it cheap and bad as that will ruin the property's name on the Wii and their own developer name. So it's a difficult decision but you are starting to see a replacement for it. Instead of going full out on the PS360/PC option, they are putting more focus on Wii exclusive development more so than they probably have done for any console. Now all of these may not be games people necessarily want, although subjective, it's not as if they aren't developing for it.

This kind of treatment will probably continue throughout it's lifecycle but the exclusively developed games are getting much better and more varied as time progresses.

They were more expensive than Pets, Horsez, or *insert mini-game compilation here*.

so that makes my comment illogical or untrue?