Okay, let's talk about motion blurr. I suppose if they have motion blurr it is because it makes a movie watchable. At 1/100 shutter speed I am worried the movie won't be watchable on the big screen without people getting headaches.
There are lots of films that use faster shutter speeds. 45 angle used in Private Ryan (1/192 shutter speed), Gladiator used the effect too. Of course neither used it for the whole movie.
That's all very true, but usually these decisions are made BEFORE you shoot the film not after you have the footage and then just hope somehow your mistakes fit the story lol