Going to the City Hall for the coronation was a method Jerome Bonaparte arrived at after deep deliberation. If he were to choose Reims Cathedral for the coronation, it would pose a problem of legitimacy for the Bonaparte Clan.
The monarchs of the Bourbon Dynasty historically claimed that their crowns were bestowed by God, while the crown of the Bonaparte Clan came from the thirty million people of France. One claims divine right, and the other comes from the people's mandate; these are not complementary claims, rather they are somewhat opposed. This would be like slapping the face of those traditional kingdoms, so after much consideration, Jerome Bonaparte abandoned this idea.
