This is important because people need to know that defending themselves within their own property is not going to get them into trouble and that no one can force entry into their property with impunity (with obvious exceptions).
An Englishman's home is his castle is an idea that should be enshrined in law. If someone breaks into your property, you should be allowed to defend yourself and your property (from uninvited invasion) by or with whatever means you choose. If someone decides to break into your property (for an example let's say it is at night), you don't have time to be rational, or to check whether or not the intruder has a weapon – you will grab whatever is to hand to defend yourself and your property and evict (or capture) the intruder. The intruder has to know that if they are breaking the law, they need to worry about more than being caught by the (never there when you need them) police. A change in law to affect this situation would cut the number of burglaries due to the fear of being caught by a householder. Using "reasonable force" is currently misunderstood. Whatever force I decide to use against an uninvited (and unknown to me) intruder is, as far as I am concerned, reasonable.