Film writers have become so subservient to plot (which is grossly overvalued)
I'm not sure what movies you're thinking of but there are a lot of plotless movies out there. And the Coen brothers hve a lot of interesting plot. BUT they have good characters and dialogue too.
A movie with no plot but a lot of dialogue is something I see film students and first timers pretty regularly. Many writers fall in love with their own words. And it's godawful 99.98% of the time.
I agree about the hems and haws.. but that's good acting and directing. When actors try to perform a hem and haw written into the script they aren't acting anymore. It has to come organically from the emotional context and the actor's they are interacting with.
I think every writer should be required to write at least 10 minutes with no dialogue at all. I think a lot of writers lean on dialogue because they aren't movie writers. Maybe they are novelists or playwrights... but they aren't movie writers. I think dialogue is overrated compared to story. I think people go to the movies for a good, surprising emotional -->story<--. Concept is still king if you want people to pay for what you're making.