I think Madden has reemphasized a valid concern about the Wii console. The concern that many have brought up. Perhaps the Wii audience is just not interested in mature games. Looking at the sales of other mature or conventional games on the system you would not be surprised by the sales of Madden on the Wii.
RE4, a game released for GC, PS2 and PC as well, says hello...
How can you expect good sales of mature or conventional games when the quality of the few there are is horrible?