So far the "core" efforts on the wii has been from Ok to weird to mediocre. Unless they made a true mainstream High Quality game "core" game on the wii THAT BOMBS then we start to make that question seriously.
And no, Madworld and Dead space Extraction and Darkside chronicles doesn't count. Nobody asked for those concepts ergo nobody bought it.
By the way, why Uncharted 2 and Borderlands underperfomed? Nobody asks that.