We recently adopted a 5 year old cat from the shelter after my very elderly indoor only cat passed away right before Christmas. We have been staying in temporary housing, a tiny apartment, and much to the cat's dismay, he was not allowed outdoors there. I have an inkling that he was an indoor/outdoor cat in his previous life, because he really did not understand why he couldn't come and go.
Now, we are staying with my parents for a bit until we can find a house to buy, because we needed out of that tiny space, and the cat can come and go as he pleases, though we do insist he comes in at night because we have a lot of coyotes here. My parents live in a very rural area in the country, no busy roads, lots of woods to explore and even though I know there is a chance something could get him even during the day, he is a much happier cat for being aloud to spend some time outside every day. I hope that the home we purchase will allow him that same freedom, but I agree with the majority of the posters here - whether or not I allow him outside depends completely on where we live. Being pregnant, I am a little worried about the risk of disease with him being allowed to come and go, but I figure if I wash my hands a lot and leave litter box duty to DH, I'm probably okay. My OB agrees with that.