That was my first "wtf" reaction. Although they don't show it in the photos, the back of a mac mini isn't exactly a fun place to have to poke around all the time. Cables etc. Especially because (at least in older models) the cables tended to get loose after a year or so and could be easily knocked out. I wouldn't want to be reaching around there to pop the card in/out. It also limits the places you can mount the computer relative to where you're using it from. Seems stupid. They should've left it out. However, I guess it provides a good utility for doing occasional tech support (boot from SD etc).