I’ll weigh in here and say that it’s probably a combination of your picture profile settings AND your choice of lens.
I’ve been shooting on some old Canon FD lenses– everyone who sees the footage goes nuts. The older FD glass produces a very organic look. I think part of it is that the camera’s sensor is SO sensitive that you get way more detail than you’re used to resulting in a very digital looking image. The older glass smooths it out a bit, without looking like a digital post effect, or like you just turned the sharpness down.
When it comes to picture profiles, I’ve found it helpful to sit down side by side with a beautiful HD still of a movie I love on a calibrated monitor. I pay special attention to the black level and color intensity.
Using this method, and a little bit of grain added in post, I’ve achieved looks ranging from crisp, high contrast HD styles like you’d see in Casino Royale to more understated, filmic looks like Lethal Weapon.
This camera is beyond capable of the film look- people are underestimating the ridiculousness of the sensor. There’s more control there than you guessed.
I’ve described the camera this way to everyone so far– the FS100 is NOT for run and gun, midrange work. It’s a professional camera for low budget filmmakers who are really into composing their shots.