Some of this seems to stem from the very essence of the concept of these Living World/Multiverse/modular/shared settings. It's why when Mike started exploring this approach to gaming in the community it solved many problems (scheduling, bodies in the chairs, and expanding/creating fun for MORE people) and scratched the itch of many basic aspects of gaming that appeals to many people. However, it created other problems for some. Notably, it's really hard to create consistency and nuanced storytelling that evolves over many sessions - it's not a fatal flaw, people have been having an insane amount of fun for years in these shared settings (clearly). I did the Living City/Living Greyhawk stuff back in the day and it always had a forced and somewhat artificial feeling, but also provided a great deal of fun for many people despite that lack of character and relationships in-world - especially for people without a consistent group back home. Mike gave up on me years ago, but this is a reminder of the essence of why I've not participated despite Mike's hard work and the community's embrace of his approach. Regardless of my own reservations given my gaming priorities, he's been the seed for more local gaming fun for RPGs than I've seen in any other era of being here (30 years of gaming - on and off here in Louisville). The insularity of RPGing just doesn't seem to exist as much here because of this community.
I know the West Marches era of LouisvilleDND or whatever isn't THAT long ago, but I never participated because those weren't compromises I was interested in making and I actually finally stumbled on a SYR accidentally when a friend on tour was playing at Kaiju and people are still having a blast in an even wider and more open format. Looking around I saw lots of smiling, laughter, and merriment in different rooms of the bar as I suffered through The Matrix and an overpriced beer waiting for the band to show up and the evening to transition to music.
However, it strikes me that flexibility by all parties is sort of essential. If you come in with too fixated of an idea, you're going to be disappointed. Whether that's as a DM from a story perspective or as a player with a very specific character that might not slide in flawlessly. If you can't operate with enough of that (whatever that level is), you're probably not going to have a good time.