Well, in a way he does have a primary power switch, since if he doesn't have the unit plugged into the wall, the main DPDT switch would turn everything off if it's in the "wallwart" position, and so he could leave the other switches on and use the DPDT for turning it on.
But, he'll still need some way to charge the batteries, meaning that he'll need a switch to direct whether the batteries are connected to the unit or the charging jack (unless he's going to take out the batteries to charge them). So, that would also serve as a main power switch, since having it in the "charge" position would turn everything off, too. So, yeah, daguuy, I guess your right.
One problem with the picture: when the switch is in the "wallwart" position, your dc/dc convertor's output is cut off, and so your system won't be getting the 3.3V.
Edit: here, I simplified it a bit. The fan'll be on only when the system is on, since the screen doesn't need it. Connected wires are signified with nodes (except I forget to put nodes on the parallel battery connections).
