The peak currents are much higher than that. The Weatronic averages the spikes out. I used a Powerbox Royal in my CARF Pitts S12 with 8 x 8511 on the ailerons, 4 8911 on the elevators, and 4 8511 on the rudder (yes I know, more servos than on a jet ), the peak currents on the ground was around 30..40 amps (small spikes). No surface was binding, all servos was programmed to give no resistance over the full travel.

If you are going to put battery packs "all over the plane", how about power on/off, you would have to walk around your plane and switch off the extra packs (and we usually don't want heavy packs at the back of our planes) ?
Sorry, I just don't seem to understand the "single wire does it all" concept, pull 10..20 amps in spikes on a single cable => lots of voltage drop

One cable to each servo => more redundancy/distributed load/constant voltage.