First of all, humans are pretty good already at "looking but failing to see" - if it happens just 1% less with machines that's got to be a good thing. (Let's not discuss the size of the 'if' here).
There's a huge point to cars driving themselves on many journeys; I could read a book, catch up on emails, etc. Etc. whilst on those boring motorways and trunk roads that make driving a chore. Switch it off when the going gets interesting or I just want a drive.
And as has been said previously, getting back from the pub will be a lot easier!
The system might also be useful for those commercial drivers who like to use their phones and computers whilst driving....and some have even been caught cooking themselves a meal on 'long boring sections' of road.
Another plus might be that could force the larger vehicles to stay in a particular lane on a dual carriageway or motorway.