Regarding the Snoke expectations, I remember that a few fans were expecting ROTS to explain the whole Sifo-Dyas/Kamino getting erased mystery that was one of the main plot points of AOTC-and it didn't.

Although the EU did eventually answer the question (Basically Dooku manipulated and used Sifo-Dyas and then took control of the project to twist it to the Sith's plan), as did the still-canon Clone Wars-ironically, in episodes released after the Disney sale (although not overseen by them).