You see, in TPM, we associate DOTF with an epic lightsaber duel. It has nothing to do with Anakin. In AOTC, we associate it with the turmoil Anakin is experiencing and his inner conflict. Basically, it was used in two totally different instances in the prequels so far. If John Williams had just used it for epic saber duels, it woulda been cool in EpIII, or if he had just used it to for Anakin's inner turmoil, it would have worked great in EpIII. Yes, but the duel in Episode 3 combines both of these elements- both Anakin's turmoil and an epic lightsaber duel. So, using your logic, DOTF is perfect for the duel.