Dangerous dogs

I don't understand why anyone would want to own an ugly and dangerous dog? We have had few deaths by the dogs in this country. Some dogs aren't so cuddly in my opinion and should be kept on a tight leash and in a place where they do not pose any threat to humans. Would anyone let a panther or a cheetah walk around in a home or street? I believe some of these dogs' breeds (rottweilers and pit bulls) are very dangerous and should not be anywhere near kids or adults. Its a terrible start to the new year for this little girl's family (link below). She was only 5 year old and had just started school. Kids are innocent. They would go up to anything and be curious about it. A kid would have no idea that the dog is going to attack it. Its such a sad and terrible news. The dog even attacked her grandmother. Its just not worth it to have a pet like this.
http://news.bbc.co.uk/1/hi/england/merseyside/6223897.stm
http://news.bbc.co.uk/1/hi/uk/6222689.stm