I don't think what the audience wants has changed that much. What's really changed is a lack of compelling connectivity and meta narrative between MCU films. The Thanos/Infinity Stone stuff was compelling, as were the ongoing and evolving relationships like Tony/Steve, Steve/Bucky, Peter Parker/Tony, Thor/Loki, Thor/Bruce/Hulk, Wanda/Vision, Bruce/Hulk/Natasha, Natasha/Clint, Peter Quill/Yondu, Peter Quill/Gamora, and Thanos/Gamora/Nebula, which raised up interest in the MCU as a whole, as if it was an ongoing ensemble TV show and everyone wanted to tune in to the next episode to see what happens next. Phase 4-5 doesn't have that, the success of NWH, MoM, WF, GotG3, and DP&W won't mean jack **** when it comes to interest in BNW because there's no compelling connection. Oddly, the main connection to another Phase 4-5 MCU film is the connection to Eternals, but Eternals was an underperforming movie and the connection is not character driven or building up to anything specific.
Literally the entire meta narrative of the multiverse saga films is "the multiverse exists and eventually an incursion will make it collapse into a big crossover mishmash". Which, sure, will be really fun fanservice and I'm sure the Avengers movies themselves will be sucessful because of it (as were the previous multiverse crossover films), but as a meta narrative it's basically nothing.