My pet-peeve with modern DSLR's is that none of these manufacturers seem to care about motion-cadence with their video offering. There's been amazing leaps with 4k video and now 10 bit image depth with the Panasonic GH5, but the footage looks so damn robotic and souless compared to cinema cameras from Arri and Red. I obviously don't expect a $2000 dslr to match a $50k Alexa in image quality, but surely they must be a…
Using an ND filter to get a slower shutter speed is the way to go. The more expensive cameras usually have a ND filter built in. Shooting at 24fps is possible on most modern cameras these days. If you want to have the ability to adjust the amount of blur in post shooting at 120fps+ allows for that workflow but it’s a pain to do. Or is it something else like a bad video codec?
Also, in film, people generally keep the shutter angle at 180 degrees. So for 24 frames per second, the shutter speed is usually 1/48 of a second.
As for codecs, that's actually where some of these cameras are making leaps and bounds. The GH5 I mentioned is capable of 10 bit recording, which means you could record ProRes HQ with an external recorder.