|Picture of iPhone 4 from Apple's website. Copyright Apple|
I suspect this is to highlight the features of the Retina display - it looks just as good at an angle. I know it's easy to edit a picture of a phone so the screen looks good from any position, and indeed many companies do this, but the iPhone 4's screen really looks like that. It continues to amaze me. I think I'll buy an IPS monitor for my next computer, but Dell's IPS monitors cost about $600.