What you are quoting is true when buttons are occupying mostly white space.
When the buttons are tightly packed, as live tiles are in Windows 8, the rounded corners clash with eachother and the negative space distracts away from the content within the tile.
Source: I'm designing a Windows 8 phone launch app.
When the buttons are tightly packed, as live tiles are in Windows 8, the rounded corners clash with eachother and the negative space distracts away from the content within the tile.
Source: I'm designing a Windows 8 phone launch app.