I think you're viewing the past with VERY rose-colored glasses. We have as wide a range of films as ever. If anything has suffered, its mid-budget star vehicles, but those have largely been replaced by streaming series like Severance and the like. We have an impressive assortment of exciting young directors, including Alex Garland, Chloe Zhao, Ari Aster, Robert Eggers, Barry Jenkins, Damien Chazelle, Ryan Coogler, Emerald Fennell, and Darius Marder (that's just off the top of my head). Plus, a lot of older hands like Spielberg, Cronenberg, Lynch, a Coen brother, Campion, Del Toro, Cuaron, Inarittu, Miller, Raimi, Scorsese, Nolan, Cameron, Scott, Tarantino, etc. are continuing to produce great films.
Criticisms of the MCU, when they emerge, are almost always leveled at the conventional cinematography and standardized color palate, so your point about atmosphere might be debatable. The storytelling and pacing, along with the casting and performance, of the Marvel films is a remarkably consistent strength. We have never seen such a run of both critically and popularly lauded films - and I mean that, literally NEVER. Actually, blockbusters in general have arguably become fewer in number but generally higher in quality, with franchises like Mission: Impossible, Top Gun, Bond, and John Wick maintaining a consistent level of excellence. When you actually compare the modern media environment, streaming series and films and cinematic releases combined, to the "good ol' days," I really don't think you see any genuine decline. You may see the reverse.