The old and very common question or dilemma among cat carers is of course whether they should let their cats roam free outside or whether they should keep them permanently indoors especially since the dangers of being outside are often greater than having the freedom to come and go wherever they feel like. Plus there is the other issue as well since cats are predators after all and they seem to prey on many garden birds and small animals and according to some they seem to be responsible or at least contribute to the extinction of many bird species or to the small numbers that they are living now. Of course this is questionable and for some this is a natural behaviour from cats which we can't really change.
Although it is true that cats were originally domesticated to keep the numbers of rodents down and therefore to protect human food resources and infectious diseases that were originated from rodents from spreading now, after all that time, they are not anymore what they used to be before they were brought 'home' by humans, wild that is.
The belief that the cat should be allowed to go outside even if she was born and lived almost all her life indoors because it is cruel and against her nature instincts it is only the belief of those irresponsible cat carers who are not capable of looking their pets properly. They seem to fit perfectly the profile of those cat carers who will easily accuse dog owners of being irresponsible if they don't keep their dogs 'under control' at all times but at the same time they don't want to know what their own pets are up to when they are outside.
A cat that lives with humans, sleeps and rests on chairs, beds, eats food that it has being bought especially for her, taken to the vet every time she sneezes, given shots to boost her immune system and protect her from illness, wears collars to be identified as a domesticated one, plays with plastic mice on a string, is not the same natural behaved cat that lived in the wild so many years ago. She has changed, evolved to a more human way of life and she depends now more and more on us for her survival. A domesticated cat therefore can live happily indoors and does not need to be outside if she there is danger and threats from cars, humans or other animals. She has adapted after all this time to live with us and she doesn't need a 'natural' way of life, as she is already have one, living with the creatures she knows, us humans. A cat is not a wild animal, is a social one like her carers, the humans.