I’m referring more to the OT in this regard, and yes, TFA really started the trend - ‘Who talks first’ and the joke about Daniel Craig dropping his weapon probably counts here - but overall the characters take the situations seriously and it goes a long way to legitimizing even the more absurd moments of the movie.
Reactions to Kylo’s tantrums, the whole shield scene with Phasma, that one line about how the force works, etc. TLJ is just continuing what’s already there.
In comparison, Boyega has pretty much patented a look of baffled skepticism with regards to TLJ’s dumber moments:
When your co-lead looks embarrassed with the BS, you’ve got a problem.
That’s kind of a warped interpretation of those moments. He’s reacting to Maz implying she been, uh, intimate with the codebreaker in the first, and BB-8 in the walker in the second. Both humorous moments, both reactions there to enhance the humor.
You mention Space Leia, Rose, and Canto Bight as being very earnestly implemented and I agree. Rian seems quite interested in being serious in the parts of the story that he likes, while treating the bits he doesn’t like as punchlines. Just little things like Anakin’s lightsaber, Snoke, Maz, Hux…
I don’t really understand why people have this impression that he’s “making fun” of things from TFA he “didn’t like” or whatever. Injecting humor doesn’t mean he’s disparaging those elements. Rian’s been very forthright about wanting a lot of comedy to keep the film from being too dark. If he “didn’t like” those elements they just wouldn’t be there at all (he easily could have cut Maz out, and given Snoke and Hux roles as small as theirs in TFA). As is he gave us a Snoke that was far more interesting and intimidating than in TFA, a Hux that was far more memorable with a more worthwhile place in the story, and a Maz that wasn’t any goofier than her TFA appearance. As for the lightsaber, Rian made it an integral symbol for Luke and Rey’s journey throughout the film… even as JJ cut and reshot its symbolic importance out of TFA.