Yeah, as you say, reality is far from the ideal. But I believe that even without those obvious problems, people still make mistakes and the extra couple layers of protection could save your life.

I was in a near crash without doing any of those things (night driving on a very fast road in an area I was unfamiliar with, and misread the shape of the road). I panicked and swerved without checking my blind spot (it was an empty road, or so I thought) and almost caused the other person to crash. More advanced blind spot monitoring systems could have largely removed the danger of the situation I was in, although obviously there is a lot that I could/should have done better myself. I think the next year's model had a HUD which showed blind spot status.