That was my feeling also. Don't get me wrong, I think it would take a concious effort to ruin the title at this point.
I did expect to see the Alien a little more aware, perhaps a little more intelligent. They don't need to see you right? Bio-sensory navigation and all that. I personally feel ducking behind a shelved trolley as it walks right by shouldn't be enough to elude the Xeno.
How is the depth of field artificial? Immersion based effects are always going to be somewhat odd given you're staring at a screen and seeing the whole picture but the feature itself is realistic. Stare at your hand or a phone and pay attention to your peripheral vision. Everything is pretty blurry outside of what you're focusing on.
It also looks like you're free to toggle between having the DoF on the background or on the motion tracker, so even if it's not a "legit reason" for some people, it's very clearly playing into a game mechanic.