It's a matter of modifying both the logic board and the chassis to accommodate the different components. It has a reasonable cost and also requires substantial

It's a matter of modifying both the logic board and the chassis to accommodate the different components. It has a reasonable cost and also requires substantial modifications to the existing accessory ecosystem and product lines. Even the smallest changes have deep and profound economical ripercussions at these scales, no matter how small they are. Companies like Apple invest a lot of money on designs and they want to stretch the amount of times they use them as long as they can.