Speaking of which, movies generally operate according to the "opposed roll" paradigm: attacker and defender roll, and the high roller pushes back or damages their opponent. Roll vs. AC is a wargaming idea, not a story idea.
So, when I say "cinematic", I mean that the tone itself is like that of a dramatic swashbuckling story. I'll explain further below, because it all ties together. (I feel that "emulating cinema" isn't the only definition of "cinematic". I apply that term to mean anything which contains qualities often found in movies, generally adventure movies.)
I disagree. Can you cite specifics? Those strike me as being normal failures and successes, for the most part, which means that (naturally) the ineffectual sidekick fails more often, and the hero is effective more often. I feel like actual fumbles and actual crits are much rarer than you think in such films. Context is everything; an action that would be a fumble in one movie wouldn't be a fumble in another.And the ineffectual sidekick in the movies always drops his sword or fumbles in some way far more often than the main hero and villain do. Likewise, The main hero or villain have critically effective hits far more often than the ineffectual sidekick does.
So whatever it is you think you mean, it isn't "cinematic".
But to really sum up, here's why I feel that crits and fumbles in such a situation showcase a dramatic tone.
In an adventure story (generally a movie, but "cinematic" is a much broader term in this context), when the highly competent hero fails, everyone goes "Oh #!%#$!". When the incompetent sidekick succeeds, everyone goes "Oh #@%^, I can't believe that just happened!".
When a disproportionate number of failures are fumbles, or a disproportionate number of successes are crits, that's what evokes the same emotion, the same feeling, at the gaming table.
Also, Lvl45DM!, good catch. Pretend I said "Charisma check".