Haters gonna hate?
Seriously though. Whenever there is something that is popular and loved by many, there will always be an "anti-group" to balance things out a bit.
It is never a good idea to conduct other activities that may divert your attention and concentration from driving. One must impose self-restraint and park aside to safely fiddle with their devices to avoid getting into potential accidents.
While the battery bank may be official, ?40 seems like a steep price for only 4,000 mAh battery capacity. I get the feeling that you are mostly paying for the HTC brand than anything.