I'm wondering the same thing, ThreeCatz. The little girl who showed up at my door has been front and back declawed, so I put on the flyer that she needed to be an indoor-only kitty. So far, nothing - but who knows why.
tezster, it might depend on the area (culture, climate). I feel like in this area, it's completely normal to let kitties go outside. I saw at least 5 or 6 different cats at my old place, a block over, all of them owned (except Mr. Casper, who I took with me when I moved).
Growing up in NJ, I never saw cats outdoors (except my own, on a leash). And when I lived in upstate NY, the only kitties I saw outside were feral, and there were very few of them. The weather's much milder here, so kitties can usually go outdoors even in January or February for a few days.
So I'm worried that the fact that I specified that Miss Kitty has to be indoor-only is going to turn some people off.