Covering the evidence...
As I have mentioned a few times before, it seems that by Ep. II the Jedi have still not dicovered the name 'Sidious' or that this being is the Master of the Sith duo. This is despite the fact that the Viceroys know this formation- heck, a whole ship full of people saw Sidious talk to them in hologram form, who also survive.
On the assumption that the Jedi would have to be EXTREMELY stupid not to have recovered this info (I would have tried every trick in the book to find out about the Sith!), do we assume that Palpatine and co launched an enormous cover-up operation after the battle of Naboo? Other pieces of evidence like Maul's ship and equipment would also have to be dealt with... could this easily be done without anyone being suspicious? The death of the Viceroys would be particularly hard to do...