Some of the people on this thread have are quite vile. 
I have two cats. They are both indoor cats and so use litter trays (which I'd prefer not to have to have ideally) and don't annoy my neighbours. There aren't really any benefits to me in keeping the cats indoors, in fact, the opposite as I have to have several cat scratchers/trees all over the place and two litter trays, plus one of the cats insists on scratching everywhere except the cat trees/scratchers.
I can't have windows wide open in the summer. I also have to play with them frequently and keep them amused, but none of that is really much different to what I have to do with my dogs and I accept pets come with their responsibility.
The benefits to my cats by being in are huge. No danger of being run over, bullied by children, harmed by dogs or other animals, no risk of FIV, being in a warm, safe, cosy environment and a longer life expectancy. They are perfectly happy to be in and get supervised access to the garden in summer.
My neighbours have outdoor cats and although I love cats and would never harm them, I do find them highly irritating. Several try to come into my house on a regular basis, one has tripped my youngest son up several times in trying to get int he door as he does. They come into my garden and annoy my hens (Imagine the uproar if my dogs got into someone else's garden and worried their livestock/pets/children) and they annoy my dogs. Yet, if my dog managed to catch and kill one in my own garden, no doubt the poor dog would be to blame...
It's perfectly possible to contain a cat to your own home or garden, but it is so acceptable in this country to let cats roam free that few people bother and just think it's perfectly acceptable for cats to do as they please. (they used to let dogs do the same years ago too.... )