Well there's the power, that can allow the Switch to run at a higher CPU frequency, allowing for better graphics than in portable mode? Just a thought.
If the switch ever gets hacked then someone would probably write some software to pull more power from the battery,making the dock pretty useless.
Granted it depletes the battery within minutes but hey, point proven.
I at least expected some hardware that boosted the entire unit.
It's essentially a hopped up overclocked Wii U controller without the Wii U then.