Has nothing to do with driving poorly or being a bad driver. There are multiple reasons to get assistance technology like lane keep assist, PCS and I will also throw in the new systems that steer for you.
The biggest thing personally is the experience of new tech. All of these features cumulatively add to self driving cars. You can have mixed feeling about this tech, but it doesn't detract from the fact that its cool.
The other thing is that even if you are a good driver, can you honestly tell me you haven't veered out of your lane even once accidentally? or looked away from the road a split second? Nobody can say that haven't. If these assistance systems actually prevent a single accident in the life of the vehicle, then it will be worth it.
And last, radar based cruise control minimizes fatigue in long hours of driving, thereby reducing human error
joking aside. I recall once when I could have used LKA in that I was driving up to Oregon very early in the morning and next thing I knew the car was riding on the shoulder. I woke up to a bump bump bump. After that I was wide awake. Luckily no one was around at the time.