My three are inside only - no choice now as they are declawed anyway. But, they have never even been outdoors, ever and so do not know it exists. If we open a door to the outdoors, they are afraid! Instead, we have a enclosed patio. On nice days, they get to go out there and think they are in heaven! It has fake "grass" (indoor/outdoor carpet) completely screened. They do their hunting, birdwatching, bug ack acking, etc, sunbathing and tree climbing (hubby built condo thingy). Our area has too many dogs and cars anyway - even if they had claws, I would not want them outside unless they were on a lead and I was with them.
If we lived out in the country AND they had claws, I would like a little flap door to allow them outside and one I could lock closed so they would be inside at night so I would not worry! (I am a worry-wart also!)