I'm definitely for outdoor cats! (Well, cats that can choose to go in and out whenever they please). As I mentioned earlier, one of my cats had to be kept in a large dog cage for 6 weeks to let her pelvis heal. However, one night she had managed to get out of this cage and tried to go upstairs to my room, which showed how desperate she was to get out of a confined space (the gap was barely 10cm wide and considering she couldn't manoeuvre easily with her broken hip, this was pretty incredible!).
I also considered keeping her indoors when she started having epileptic fits 1-2/day, cos she loves climbing trees and walking on the roof of our house (which is sloped), and I was scared she might have one when she was up any considerable height. However, she did stop having them (so I'm assuming they started from her licking her sister's neck soon after we'd given them both their flea treatments).
Apart from these 2 situations, I've never wanted to stop me cats going outside. They still have wild instincts in them (including killing and bringing nice dead presents into the house for all of us to see), and I think it's cruel to keep them indoors unless there are extenuating circumstances.
When I'm at uni (in a 2nd floor flat), I miss my cats, but wouldn't dream of bringing them here or getting another cat, cos I know they wouldn't be able to go outside (plus I wouldn't want to move my cats when they're so accustomed to family's home).