Ive seen someone with the quote regarding Caesar as " not feeling safe , save only with his legions" ( I paraphrase-Cicero I think), in some ways it would seem that once Caesar was in the field the Gallic wars were already decided ,as an enterprise, in his mind. The difficulty as FV alludes to is that the moral high ground probably has no occupants in our contemporary way of thought, Caesar was at least Roman in his prosecution and thoroughness ( if you are a critic): would his opponents have cared about Gaul? One imagines FV is correct here-Gaul is a canvas for (ambitious) Romans to work out their political designs , not a moral paradox and the army is the implement expressing the Romaness of their actions.
For Gaul, Germania and Brittania the sooner you get into the "executive class" of Roman influence the better.