I'm strongly in the anti-motion-blur camp, despite never minding it in other games. I think it mainly has to do with two things: the 30fps cap, and the extremely high level of detail in the world.
Switching to performance mode, the motion blur is much less distracting, so that's all I can really say about that. I guess with close to half the frames to work with, your brain is much worse able to understand the image in motion.
The detail is a big factor: the game's assets are so high quality, that you're really focused in on small details more so than in most games. When the slightest touch of the right stick blurs the entire screen, it's hugely frustrating to not be able to make anything out in scenes that have the potential to look so good and display such complexity. The game doesn't do much to make its world "legible" by having interactables, characters, etc. pop out in any way, so you really want to rely on being able to parse that detail, but the motion blur makes it impossible. I find myself constantly stopping still to take in the scene, much more so than I would in other games.
Lastly, John made a comment in the podcast that he was confused as to whether players were constantly moving the camera. I found that odd— the answer is clearly yes, that's how pretty much everyone plays 3rd person games with a free camera during exploration. Not so much in combat, so the blur isn't really an issue there (admittedly that's mainly down to the fact that you're only focusing on Clive and the enemy, rather than the whole scene).