I think you have to make a decision based on your environment and your cats.

My grandmother lives on a busy street so she keeps her herd indoor only.

My Mom & Dad live just outside city limits, several hundred feet off of a moderately traveled dirt road and their little darlings go in and out as they please. Some of the fat/lazy ones rarely go outside and spend most of thier days on the back of the couch. The younger and friskier ones of the group play all day in the popcorn tree off the back porch and chase birds (quite unsuccessfully actually), but they always come in at night. One even like to go out and hop up on Mieko's (the horse) butt and ride around the pasture.

My uncle on the other hand only keeps ferals. He lives on a road in the boonies (I'm talking maybe three cars come by the house, and that's on Sunday) and all of his fur-friends live outside only. I don't think they would understand what to do in the house. He keeps one of those 12x12 utility sheds in the back yard with a hole cut in the floor for a cat door (too small for cyotes (SP??) or any dog/fox big enough they couldn't take on. Some of them are pettable, most are not, but I'm sure all of them appreciate being given food and shelter. Of course we're in L.A. (Lower Alabama) where the coldest we ever really get is a light frost. A hard freeze is an event.

My babies, on the other hand were declawed by their previous mommy so my choice is made for me. Inside only. I wouldn't mind letting BooBoo in the chain linked front yard (he's too fat to jump the fence) but he's just not interested. He will just sit and stare at an open door and not even consider making a break for it. I'm not sure how Kelly feels about it; she's still under the couch.

Some cats love indoors. Some cats love outdoors. Some cats insist (very loudly) on being both, and you must get off the couch at their beck and call to accomodate them.

BOTTOM LINE: Cats are adaptable. You and your cat have to decide what is best for ya'll and for your unique situation.