I own three guns. A rifle, and two shotguns. The use for them is for hunting. I hunt because, at least where I live, I can't buy deer meat from the super market, and I really like deer meat. Also, if it wasn't for hunters, many animal populations would get out of control. Hunting is important to maintain a balance. Guns could really help Australia with some pest control, such as rabbits.
I also lived on a farm for quite some time. Guns are quite important for defending ones farms animals. Coyotes, wolves, mountain lions, etc are problems. A gun helps that problem. Seeing ones geese, or calves dead from an animal attack sucks, and can become quite costly. Even rabbits, raccoons, skunks, etc can be a problem. Have you ever seen a rabid skunk? A gun is a lot better to deal with that then a baseball bat or etc. Or what about an angry badger? A gun is a solution to that problem.
A gun collection is generally quite safe. Most people do not leave them loaded, and are kept out of the way. My guns are kept in my room, unloaded, and covered, while the ammo is in a separate room. My father keeps locks on his, my father-in-law keeps his in a gun safe. Guns are relatively safe as most people make that so.
Guns do not make criminals. Take away our rights to own a gun, what happens? One, there would be an ecological problem. The population of deer, for example, would sky rocket and become a nuisance (for many farmers, they already are). Most likely, they will exceed the capacity limit for many areas, and thus cause even more problems for the ecological system in that area.
Two, criminals would still be getting their guns, as many of them are getting them illegally anyway.
Three, baseball bats, knives, swords, bow and arrows, rocks, cars, etc can all be used as weapons just as effectively. And most of those are a lot easier to get then a gun.
There is nothing wrong with guns. They serve a purpose.