In TPM Maul says, “At last we will reveal ourselves to the Jedi, at last we will have our revenge”
So they will gain revenge by revealing themselves to the Jedi? This line doesn’t do much except reinforce the aforementioned rule of two. It is inferred that the Sith want revenge, but no motivation is revealed at any point in any of the movies.
Not to mention the line brings to mind images of Darth Maul standing before Yoda opening his raincoat.