I remember reading/hearing Jonathan Ive say that he takes as much time considering what to exclude from Apple products as he does to what to include. Apple has the luxury of total control of its hardware. It's more of a design decision, in the quest for elegance and simplicity.
The PC components market is driven totally differently, with each manufacturer competing on features. Apple does not have to compete with any other company in the same way, as it has total control of what goes into its computers (hardware and software).
This is why it takes so long for legacy features to be deleted from PCs (like parallel, serial and PS/2 ports), while Apple can just choose to stop using old technology on a design basis (like floppy drives, ADB port, Motorola and PowerPC compatibilty, etc).