* So nothing can get stuck inside. * So valuable space isn't used up inside the computer. The motherboard in a macbook air is tiny. The extra half-height of the SD card that would be necessary for it to go all the way in is significant.

Either way, as it stands Apple hasn't provided a spring-loaded mechanism, so they have to do something like this. They only made the removal tool by popular demand: in the Kickstarter they were just advising use of a paperclip, which seemed reasonable. Over-engineering is always a danger, especially when you're fighting to just get a product shipped.