The Victor speed controllers are given their logic supply directly by the 7.2V source. My team learned this the hard way while trying to get servos working, early in the build period. I agree that a more ideal design would have used either the 12V source
or the 7.2V source as the logic supply (and main drive for servos, uck).
That's a low-level "why". You'd probably have to talk to IFI for a higher-level answer to the "why" question.
