I think that Disney knows, and is building around the idea, that Star Wars is more than just the movies, it's a universe.
I think that the movies give enough information so that the general public/new audience can follow the story. My girlfriend really enjoyed TFA and TLJ and never bother with questions like ''what is the Resistance, really? Where is the First Order really coming from?'' she had enough information to enjoy both movies and understand what's going on. But if you're a fan and want to dig deeper, you'll have to look into other mediums (books, comic books, animated series, video games), or take a look into the Star Wars wookiepedia.
They already showed that they are using cross-media with the apparition of Saw in Rogue One. You can enjoy Rogue One without knowing where he's coming from, but if you want to know, you'll have to look into the Clone Wars and Rebels. And now, Solo's big reveal is the biggest contender as far as needing to watch other medium to understand (I would talk about it if I knew how to make spoiler tag, but since I don't, I'll leave it at that
). I was personnally pleased to see them go this far with this approach.
I don't think that's a storytelling failure, I just think that they are experimenting with the cross-medium story-telling to build their Star Wars universe. This allows them to not have to bother with explaining every origins in the movies, because they know that eventually there will be a book explaning it in more details. We don't currently know about Snoke origin or how he became the leader of the First Order, but I'm sure we'll get a book about it in the future. But to enjoy TFA or TLJ, I don't think the general audience really needs to know about it, he's the bad guy at the head of the First Order, and that's all that really matters (not talking about the hardcore fans here). As far as world building goes about the Force Awaken Era, I think that they are waiting after the release of Episode 9 before going into it in more details. And we'll soon get a Resistance animated series, it could bring a couple of answers to where the Republic really stood before TFA and what the Resistance really is.