I agree with Kara , a house cat is a domestic animal , not a lion , you put in the house , lock the door and expect it to be happy .
And if they have been indoor only for their whole life , they don´t know any better .
The argument , some people use , that cats need their freedom is something , you look at from a human point of view .
If you have a pet , you have responsibility and letting a cat roam (which they will) is not taking proper care of it .
Plus , there are cats , who don´t want to go outside anymore . I pulled one of my cats out of a river in the middle of winter after some a... abused her , burned her whiskers off and then dumped her in inside a garbage bag .
And you can tell , that there is no way , she would want to go outside anymore , she definitely had enough of her share of the free life outside !