You make a fair point about cultural conversation being important. I think that conversation is happening, but the focal point shifts from one generation of creatives to the next. It's an important part of cultural dialogue, not just reaching the same targets as previous works, but finding new targets, new mediums and methods of expression.
We saw the shift toward a more fractured landscape happen in music long before movies. If you grew up hearing the Beatles on mainstream radio, listening today might feel like a cultural low point. And that feeling isn't baseless. But treating the Top 40 as the whole of music ends up missing the new developments happening outside that narrow slice.
We're seeing similar shifts in film. The Blair Witch Project and Once Upon a Time in Mexico heralded the age of accessible digital filmmaking, leading to an indie boom that's still rippling out. Everything, Everywhere, All At Once showed that ambitious, effects-heavy filmmaking is no longer tethered to the traditional studio system. Those are the high profile bellwethers -- indie bands that sneak in a radio hit -- but I think they reflect the wider landscape of passionate creatives better than, say, the new Jurassic World.
So yes, blockbusters aren't what they used to be. But judging the health of the entire medium by looking at those is like judging transportation by looking at horse-drawn carriages after the arrival of cars. It focuses on what's leaving instead of what's emerging.