Could someone post a picture of the icons for Mario Galaxy 2 etc. featuring this supposedly missing "Wii" logo? Because my interpretation is that they're referring to this:
And it seems likely to me that the Wii logo is just a generic "frame" around the icon, not a part of the icon itself.
There is a problem with this theory: the Twilight Princess icon is not the same aspect ratio as the icons above, so it wouldn't fit inside the Wii frame:
The plot thickens. It's a perfectly square icon. In other words: