DJI gets to me even a suggestion that should equip the fly LIPO charger with 2 USB sockets to fit the 5 volt charging voltage for the transmitter and wireless amplifiers to provide.
My notebook is actually too good to me as a charger.
And add a 2. USB cable  to load the remote control transmitter and the WIFI amplifier  at the same time.

Oh yes, this is a nice feature! Do it.

+1  Agree, even some laptop chargers have these.

Yes I was surprised to see they provided no way of charging the extender.  It should also charge quicker.