Nitpick: if 50% was the new 100% then the supercharge option would be to 200%, which sounds even better :)
Better yet, all devices, phones, tablets, notebook computers, headphones, speakers, ... should automatically stop charging at about 75% and then continue to run directly off of the wall. I used to think that's what all devices do because that just seems like common sense to me.
Maximum charge state is some percentage below the batteries physical maximum, and maximum discharge is state is above the batteries physical minimum.
There's a bit in this Wikipedia article[1] that state charging Li-ion batteries beyond 80% can drastically accelerate battery degradation.
1. https://en.wikipedia.org/wiki/Lithium-ion_battery#Charge_and...