You are essentially saying that Episodes 4, 5, and 6 are poorly written then. There was ZERO background on Palpatine (Emperor). Same for Yoda and Vader as well. We did get them later though (years later) which is what I mentioned may happen with Snoke in future episodes.
So many Star Wars fans ripped on Lucas for episodes 1, 2 and 3 and said Lucas lost his way, yet now they trot out how Lucas is upset with Disney and how his stories would have been great. Was Zahn not upset with all the material Lucas did not use either? Sure, it would have been cool if Han and Leia had twins and they become ultra powerful Jedis and if Luke had gone to the dark side and then come back and the grey Jedis and all the cool stuff from the EU, but they didnt go that way. And I would bet dollars to doughnuts that if they had, the same fans who are upset now would criticize them for copying the EU and not being original.