How much did episode 4 tell you about its universe? Part of the excitement was the questions that only got got revealed in the later ones or never touched upon. If for one knew as little about the Empire after episode 4 as I did about the new order in episode 7. Less is more and you have to think about this as a trilogy. Kylo is defeated by one with no training yes, but one with such high power in the force that she not resists him, but also reversibly affects him instead. I would argue that this character also goes deeper into daring territory as he is the first sith we see in the movies having an internal struggle. The rest has been bad. And all bad.
As for rey. How much did you know about Han solo, obi Wan or Leia's past after the first movie? Not much.. I get that you want a continuation of the old universe, but this isn't what they are doing. You are getting the same universe but in a galaxy slightly less time ago with new rules and mysteries.