For when you're playing on the TV I guess. Does this thing not support headsets for TV play?
I doubt it, smartphone/device fixes both the "talk to thing" problem and the touchscreen for typing problem. That's why they went this way, probably, and a tethered headset leaves you unable to type.
Trying to figure out if, on the go, the console will tackle these on its own, though, as it may well given the jack's capabilities. It can obviously do the touchscreen for typing part.