It’s actually worse now than it was in the time of the Prequels. In TFA, we’re starting with absolutely no idea what has happened in the intervening years and nothing in the movie properly explains it. Luke Skywalker is missing... why? Oh, his nephew murdered all his Jedi... but that still doesn’t explain why Luke is…

You don’t really need an explanation of who Grievous is. I only kinda halfway watched some of Clone Wars. I got it. He was a big Separatist hero. I also knew I could find out more about him if I wanted, and never once felt the impulse.

And Lucerno’s prequel books led right up to it, too. It was masterfully executed for the Star Wars fan, and shittily done for the casual viewer.