As much as I hated it at times in ACIII, I think I would have preferred them change you back into the default Assassin's robes for cutscenes. Though, I didn't like how they swapped the colors back, even if you were wearing the default robes, as I much preferred slinking around in the white/red variant.
They used higher-resolution models for cutscenes. That's why, all of a sudden, Connor looked super detailed in cutscenes. For AC4, I believe they use Edward's model all along.