I don't know why Presonus did that...there are several 'zero latency' solutions out there that have this problem.
I have long been fond of the Focusrite hardware (I have a Saffire Pro 40) and their solution. They give you channel-by-channel pan for both normal and zero latency monitoring, as well as having a loopback feature that you can push a custom mix to with zero latency...full stereo...
...just a tip for the future