Why did Apple abandon the original sensor cover?

[boovish]

When I first saw the white iPhone 4 I liked that silvery sensor instead of the BlaBar. Why did they change it? And I know about the yellowish color on the original paint

 

[KaterinaM]

I think only Apple may answer why they have decided to make such changes. But new iPhone is a mosaic of ideas and design solutions, so don't be surprised )

 

[boovish]

Also, I would like to know where I can get a white iPhone with this silver light sensor.