Your home is were you should feel safe and secure. It is a place of sanctuary for you and your family. For someone to invade that illegally, for whatever reason, should be instantly in the wrong and the home owner should be entitled to protect it. There is no decent reason why anyone, other than those allowed, should be allowed in your home. Therefore the home owner should be allowed to deal with the problem without worrying about the possible consequences.
With regards to self defence, I do understand reasonable force, but the amount of different situations makes it impossible to define. It should be changed, redefined or got rid of. A know of someone who is or was being prosecuted for protecting his pregnant wife. He knocked him unconscious with a single punch after he pushed his heavily pregnant wife and he is being prosecuted for assault. How is this fair? What man would not have done the same thing in the same circumstance?