Bugging out should be an option and should be planned for, there may just be an event to where your house is just not going to be a safe place, it is like comparing it to the old analogy of having all your eggs in one basket. The bigger issue is actually making the decision to go, your home is home base it is where you are best stocked and most comfortable and under most circumstances the best place to be, but outside events such as certain weather or man caused event such as rioting, disease, fire, Govt telling you so.... There can be many reasons to have to leave.
True, that is what most people would do, as long as they have the supplies to do so for an extended period of time, food, water and heat. If you run out of those then what, you might have to leave if you can or you need to be re-supplied. Communications will be key.
Having the BOB for the car is a good thing as long as it is your car that you get to bug out in, what if the car for some reason is not available and you have to go on foot, thats where the personal BOB comes in, while not as good as what you have in the car it is better than nothing.
Covered in the above but again there are just times when you have to go.