The average burglar has no intention to harm anyone. All he's trying to do is slip into your house unnoticed and make off with your stereo. 9 times out of 10, if you make yourself known, he'll run. 1 time out of 10 you might get a real maniac, who either A) is there to harm you, or B) will decide he has to silence you.
9.99 times out of ten, if you're inside, and there's a guy trying your door, and you turn on your porch light while pointing your firearm at him and tell him that you are armed and you intend to protect your family, he'll run like hell.
Thus, he does not have to die, and you do not have to live with the guilt having unjustly killed some poor *******.
The remaining .001 times, he's confused -- either on drugs or crazy. Both of which are very sad cases. And you might have to kill him. In which case you will know you did everything you could. You gave him fair warning.
I totally agree that one has the right to defend one's family, self, and property (in that order). But there's a point where the crime doesn't fit the punishment. In this instance, I don't know if it does or if it doesn't. If the homeowner did not make himself known, and if the burglar appeared to be unarmed and there was no reason -- other than the fact that he was jiggling the door at three a.m. -- to think he meant bodily harm to anybody, then killing him might not fit the crime.
Certainly I don't think committing a common burglary would warrant a penalty of death.
I don't think your right to defend your property (with gunplay) is absolute.