I was playing Bendy and the Ink Machine, and the game seems to run better without the motion blur.

But why do developers do things that so many people dislike?  Because it looks good in static media?  Like, I've recently learned that TAA can actually be good if someone comes along with a mod to remove some of the blur.

Give us some answers CGI!  Answer for the sins of your people!

Motion Blur is awful E_E I always turn it off.

The only time motion blur makes sense is to blur rotating objects like wheels and helicopter blades. Anything else you can track with your eyes in real life and see without blur. Road surface shooting by excepted, however you still get detailed glances when you focus on the road surface in real life. I;m glad motion blur hasn't made it to VR yet, it wouldn't make any sense there. Just like dof. (Unfortunately real chromatic abberation comes with the lenses /)

Nope

I turn it off 90% of the time

I hate that effect, it completely breaks the games for me. It's always off when I can and I avoid playing games that have bad MB (very good implementation of motion blur is tolerable, still worse than off though, but those are very rare).

I stopped playing games that I bought because of how bad the motion blur was so now I carefully pick the games I buy. That and grain filter are literally a deal breaker for me.

That right there is why it's used. Most of the time it's a cost saving measure because using high quality assets cost money.

when it shake my hands in front of me, I see motion blur.
So, why not? is a effect of our real observation of the world, why not including in games, if one of the most prevalent premises of games is a virtual simulation of the real world?

When you follow you hands with your eyes, do you still see motion blur ? That motion blur you are talking about will be created anyway by your eyes when you don't track a moving object in a game, no need to simulate the effect as it will be done by your brain.

But motion blur shouldn't normally be used to simulate an effect but to hide the judder any low framerate will cause on our screens. But unfortunately many developers use the motion blur (and CA and grain filter) as an artistic mean to make their games look like old movies. Currently in the videogame industry It's more artsy. The videogame industry has an inferiority complex compared to the older movie industry. So they want their games to look like old movie to elevate their games.