Well.. actually I do. At the moment I have to have 2-4 battery packs for some jobs, which is a hassle I would not mind getting rid of.
It might be suitable for someone who wants to record sliding down a snowy mountain or a short jog on the beach... but if you want to _use_ it, that 20 minutes is not much.
The best I can make out of that 20 minutes regarding useful imagery is around 12-14 minutes, and that is the best case scenario.
So, bottom line, I would love if they put that much effort in battery longevity they are putting into other areas.