The consistent narrative I'm seeing is JL is that it's much better than the other movies, with the exception of WW, but the CGI was weak and the large reshoots by different directors created an inconsistent tone. I see people calling it a financial disaster, which it is, but I honestly don't see critics calling it a disaster as a movie. Even the bad reviews I've seen come closer to 50/50 reviews.Because it was so damn good they couldn't believably trash it? Kinda like the Saints winning 6 in a row, and all the talking heads are like, Ok they're pretty good, but they're not THAT good, then they go into Buffalo and run for 300 yards and win 47-10, so what bad thing can you possibly say about that.
Do I think there's an outright "conspiracy", no. Do I think there's an unfair narrative being perpetuated because it's "hip" to hate on them. Yeah, I do. Even you've mentioned that JL feels like a 70% movie to you - opening night I read 6 reviews and all 6 were positive with caveats, but still overwhelmingly positive. Now people are acting like JL is one of the biggest disasters in cinematic history. These movies have flaws and certainly it is fair to point them out. Even WW wasn't totally perfect - it's the exaggerated critcisms that are annoying. I posted a link earlier to a Hollywood Reporter story that called it "tiresome" which resonated, at least with me. it's the same as that "Saints can't win on the road" stuff that we STILL hear, even though the last time the Saints were any good they won a road playoff game in the cold and gave the SB champs all they wanted at their house. It's just a mindless lazy default to a particular popular narrative.
YMMV though - I've never been Mr. Hardcore Comic Book guy so it's not sacrilege to me when one of these flicks comes up short of ideal.