I mean seriously, there's a lot of "why doesn't Apple do this" type questions out there and MOST of them come down to 'because they make more money NOT doing it'. Examples include...
Not to mention $100 for an extra 8GB of storage, whereas an 8GB SD card is around $30. And over time, their profit margin is even higher. Plus having media on a removable card would make it easier to swap songs, etc. But my Nokia had this ability.
And Bluetooth Stereo (A2DP). Apple won't support this, at least until they have a headset to sell...and not a moment sooner.