Those laws are a delineated response to a few places--New Jersey, NYC, some others--where it was decided that property is "not worth fighting over" and one should "just leave the house."
Of course, once OUTSIDE your door, you're less safe. And it encourages burglary.
The standard American legal rule, based on old English common law, is that one may use deadly force, "under circumstances where a reasonable person would fear for their life." This is a valid argument in most investigations, grand jury trials and criminal trials. Few prosecutors, even in places where guns are officially banned, will attempt to prosecute you for saving your life by shooting a burglar coming in to your house.
Virtually everywhere, someone committing forcible entry (A felony), is legitimately considered a threat. The new laws just codify that for the clue impaired.
The "Castle Doctrine" (A man's home is his castle") simply codifies that at home, or in your car or on the street, you are NOT obligated to run away (Sure. I'll just leave my 5 year old standing there and run. Criminals never attack kids, after all
) from a perceived threat, and may use deadly force to defend yourself or another.
This doesn't mean you can shoot a drunk who's staggering around. However, if someone raises a knife, club, etc, and threatens you, it's legitimate to assume they intend to carry through.
We just passed such a law here, though it's a formality. For example, the only attempted carjacking I can recall was a fleeing felon from out of state. He grabbed a car at the lights, pointed a weapon and demanded the driver get out. The driver got out, drew his weapon and shot the felon (Wanted in several states) as he sat down. The prosecutor declined to charge the car's owner, citing it as reasonable to assume said felon was an immediate danger to public safety.
We generally don't lock our cars or houses around here. Actually, I just wound up the windows on my van and locked it--storm moving in. It's been open for three days in my driveway, and I have most of my merchandise in it for an upcoming show.
The same van was broken into in Chicago, where weapons are illegal, in a gated and fenced hotel parking lot with guards, and I lost the stereo and a crate of knives.