I'm pretty late for this discussion, but I still believe that in these kind of grand scale sequels there needs to be a balance between the old and the new.
1)
The NEWI was totally fine with the fact that the old "extended universe" stuff wasn't used in the new trilogy. While I have a great amount of games, books and comics about the EU, I really felt that it would have been boring to watch movies about summarizing the "Dark Empire" or "Yuzhaan Vong invasion". I wanted these movies to bring something new to the table, something to surprise me.
They succeeded - kinda. I mean, I never expected the "Force Awakens" to be a such carbon copy of "A new hope" that I was genuinely flabbergasted. It was a huge surprise, and not in a positive way. Starting a new trilogy after 10 years with a blank slate, and this was the most ambitious/interesting story that they could imagine? They made a remix of ANH events (without Luke even) instead of bringing back old characters to have them try something new. A great deal of watchers noticed this and rightfully criticized TFA as a
lazy sequel.
And then comes TLJ. There is no doubt in my mind that the theme of "overt subversion" (greatly explained by
mjn.mixael) in TLJ is a direct consequence of the critical backlash of TFA. I bet Johnson saw all the comments about TFA being a mindless rehash (or even a pure fan service / fan fiction movie) and decided to go brutally 180 degrees into the opposite direction.
"You thought there was too much plot fan service in TFA? Alright then, we will remove it ALL in TLJ! Got you know, didn't I?". I'm convinced that at some point there was a somewhat different overaching plot in the new trilogy, and that it was changed just before the TLJ production started in order to simply subvert the viewer. So many "gotcha!" moments now, that it became frustrating. I mean to who is this kind of movie made for? The old audience, the new audience, or the film critics? Seeing the Rotten Tomatoes score, I really felt that it was mostly the critics with their insatiable need the see every big film franchise "deconstructed" that got most out of TLJ.
2) The OLDThe old characters were one of the most important selling points of the new trilogy. I mean, who wouldn't want to see the old stars (Han, Luke Leia) to return to the big screen, one last time? That was the main expectation, and the reason many of the old fans bought the tickets for. TLJ outright mocked these people, and as a film it's of course "artistically" allowed to do that, but as a business practice it's never a good idea to insult your own base audience. Somehow I've seen this same kind of audience/customer mocking in contemporary video games too, but that's a totally different topic.
One has to wonder what is the motivation behind this "mocking". TFA only gave a laughable 10 seconds of Luke, and in TLJ the character was first ridiculed and then killed off. Leia almost had memorable and emotional death on-screen that we all expected after Carrie Fisher's death, but instead she turns into a flying superman and is still unceremoniously killed off-screen before IX. Han Solo is dead and he never got to meet old Luke. With the old cast gone, the reason to see IX is gone for many.
I also feel bad for Mark Hamill. Out of thee three old stars he was the most inspired and pumped-out to see himself returning to big screen. You can see his enthusiasm in many interviews and panel discussions prior TFA. "Luke" was the starring moment of his life, and a major alter ego of his. He knew his character inside out and what he represented: The youthful optimism and the attitude of never giving up. After TLJ Hamill has said many times, that this TLJ version wasn't "his Luke". He also threw a few passive aggressive statements against the movie.
"Let go off the past. Kill it if you have to". TLJ has definitely succeeded in this, but I don't think the payoff was worth it this time. I mean, if there was a better opportunity to "kill the past", it would have been in the IX movie. But this opportunity is now wasted and there is hardly any reason to see IX (especially since the plot points have stagnated). The best thing IX can do now is to skip 10 years, put some makeup on current gen actors, and focus on the young boy at the end of TLJ who's going to be the next major force user.
CONCLUSIONThere is no balance between the old and the new in these 2 movies. TFA is too old-like with its plot points with barely anything new to show. TLJ respects nothing about the past and is haphazardly running around with its plot like a headless chicken. But yet, I don't think that they are the "worst movies ever". I even prefer TLJ over TFA, because it at least wasn't as lazy. People will talk especially about TLJ for a long time - the same way as Neon Genesis Evangelion is still discussed (which curiously enough is one of my favorite shows).
P.S This became far longer than I originally envisioned. I might have even gone to the topic about "What do people generally want to see in their movies, and what kind of experience is actually worth the money", but then I realized that I had opened the Pandora's Box and removed the whole section.
TL;DR As movies TFA and TLJ are polar opposites, d'uh!