It's more like they refuse to move out of the family friendly mold. And yeah, they do have Metroid: Other M, but does anyone expect that to be controversial enough to get any higher than a T rating? I really don't think with their current success that Nintendo would have the guts to put out edgier games like Heavy Rain.
And you can say the other companies are trying to do likewise to an extent.
Microsoft is certainly wanting to appear more family friendly as shown by their E3 this year.
And Vivid Video has been wanting to do something with Sony for the last couple of years but so far Sony has refused.
Keeping a family friendly appearance might lead to more sales but it really stymies gaming from being able to evolve as a serious artistic medium.
Where twould world of literature be as an art form if you only had Archie and Mickey Mouse comics and no Naked Lunch or Ulysseus?
