House cats should be just that, house cats. Their environmental impact is detrimental. Plus, all of the neighbor cats shit in my raised bed gardens and piss me off.
Yes, that wonderful, fertile cat shit full of Toxoplasma and other parasites. What a great addition to my garden! Not to mention that wonderful feeling and smell when your sink your hands into cat shit while prepping a garden bed.
Your other point, in regards to keeping populations under control, is way off the mark. http://www.nature.com/ncomms/journal/v4/n1/full/ncomms2380.h...
Keep your cats indoors, people! They're great pals to have, but inside.