My opinion is if you live in the country, and you want to let your cat roam, that's fine, but if you live in a suburban neighbourhood, that's just ignorant. I'm tired of the cat crap in on my lawn, my wife's cats going nuts when the neighbour's "outdoor" cat comes to the windows (especially at 1 am!), and the damage to my screens as it tries to get my wife's cats, and the muddy prints on my freshly waxed cars, or the scratches where the little idiot either mis-judged it's jump, or was scared by something and tried to get traction. Now, when I see it around the house, I let out Daisy in the hopes it'll stop coming around. I've tried talking to people in the nieghbourhood, and in thier selfish and self-centred way, "Oh, it's just a cat!". Well, you know what? You aren't going to pay for my car, or my screen, or go to my job for the day when I'm tired from being woken by the cat, who scared my baby and I had to try to get back to sleep. I've now got a two-stage approach. If I have a cat that continuously comes in my yard, I attach a note to the collar, "Next time I catch you cat, you can pick him up at the SPCA". And then if it is still a problem, I borrow my buddies humane traps they use to relocate problem racoons, and I take them to the SPCA. Sorry, but unless you'll be okay with my pitbull running around your yard, keep your damn cat in your own yard! (yes, this has been an issue for us lately. Can you tell?)
As for letting them outside, Cheryl takes her cats outside, but they stay in the yard. Not only do I think that's okay, I think it's a good idea.
Hagar:"What kind of dog is that?"
Man with dog:"He's a nice dog!"
Hagar:"You know, at the end of the day, that's always the best kind."