Spoken like someone who's never had to interact with a designer. A designer will tell you the exact ratio the radius of the rounded buttons needs to be with respect to the height, and explain that this channels energy from the Earth's ley lines that resonates with the frequency of the vibrations of human brain waves, creating positive associations with your brand. And after hearing all that, the client will NOT be satisfied just bunging in Mozilla's standard gray buttons from the Windows 3.x era.