a Club Nintendo prize
Where it'd be too late to celebrate the 25th anniversary, which is, you know,
the entire point.
available in stores
Where it'd be relegated to the strategy guide rack and sit for all eternity.
By releasing it with
Super Mario All-Stars, they simultaneously put it on game shelves, where it'll sell by virtue of having the Mario and Wii names on it, and rerelease a collection people have shown, on numerous occasions, that they will buy. Even for thirty dollars, which, again, is more the cost of the bonus goods than the game itself.