This is really a discussion about nothing. We all already knew that the Wii-userbase mainly bought first-party titles while the more capable consoles got the best third-party support.
"The question is the following : with so many people playing the same games, can Wii still be called the leader of the generation?"
No, Wii can't be called the leader since so many people play the same games. *near-lethal facepalm*







