I guess because this is the only time Anakin has used the Jedi Temple phone system to call the Emperor and discuss mass murder. I do so like the provenance of this scene -- it demonstrates that the Jedi spy on all communications going out of and coming into the Temple, and keep copies of them (for blackmail?). They really are a wacko cult. I think the peg-knocking-down of the Jedi and the quasi-rehabilitation of the Sith/Empire was the one good thing, story-wise, in the prequels.