If you live in a nice rural area where the cat is free to roam in a wonderful natural environment feasting on rodents, lizards and small birds, well go ahead and let your cat be cat. As a matter of fact, domesticated animals like cats and dogs yearn to have that nice open area where they can explore and finally get to let out the animal in them. Whether it be playing, hunting or just satisfying their curiosity.
What many cat owners fear is that if they let their cats out in the yard, the cat will wonder off and probably never return. But guess what? If the cat did that it was never your cat in the first place. Or the cat may have been captured or sustained injuries outdoor. Yes, those are extreme negative things which can happen if you let your cat roam outside the yard even if your yard is fenced as cats are really great climbers and can easily scale large fences.
Cat owners who live in the city will think twice about letting their cats out as the possibilities of endangerment have increased a hundred folds. Stray dogs will hunt down and attack cats and many of those attack on the cats end up that the cat loses its life or become terribly maimed that the animal has to be put down.
So the city is not the safest place to let your cat go outside in my eyes. Pets and city life also deprive them of a whole lot of animal instincts. Many are confined to a small area and live and die a boring life. Even though many pet owners do give their pets drive outs but still restricts them in cages.
At the end of the day, you are the owner of the cat and you should understand the environment in which you and your cat live. Is it safe or isn't it? Take a look around, mitigate the possibilities of your cat getting hurt outside. Ensure the cat is not just able to waltz in the street at the sight of a man eating the smelliest tuna sandwich. It is up to you to always keep your cat in a protected and safe area.