Layout of Physical VS Touchscreen Keyboards

Hey,

Does anybody know why RIM has two different keyboard layouts? One for touch screens, and another for physical keyboards.

By layout, I really just mean why alt and ^aA are swapped. On my playbook, I'll get used shift being in one place, and alt in another. Then I goto use my phone.. and it's reversed.

Looking at all of the pictures of the NEW phones, it seems they're keeping this differing layout? Is there a technical reason for this? I'm always confusing one for the other because they're never in the same spot. I wish they'd just pick one spot and stick with it.