Yes, I do agree that Basch is still one of the major players but I feel the zenith moment of emotional expression in the game is the Sun-Cryst scene at the Pharos and despite Basch and Balthier both getting some great moments, its the part where Lady Ashe makes her final decision that is the centerpiece of this moment.

Its not just the fact the plot is about her situation its also that the main conflict is more about Lady Ashe deciding what to do. Should she get revenge or save her kingdom? I don't feel that Basch or Balthier have such moral dilemmas, they both have made their choices of what to do long before the game started and both stick to their code. Ashe grows while Basch and Balthier are just plain awesome.