Indoor vs Outdoor cat - Why are there more "house" cats now?

Ten years used to be a good lifespan for a typical pet cat. Now it's fifteen to twenty, partly becuase if better nutrition and vet care, but also from keeping them inside more. Yes, it's a trade off; limited freedom for safety. That's why we need to go out of our way to make the indoors more interesting. Sometomes just having another cat or a dog for company is enough. Other times you need to hide portions of dry food around your house for them to hunt for, even puting some into treat-balls or puzzle-boxes so they have to figure out how to get it out. Also, rotating toys so there's constantly "new" things to play with. A birdfeeder to watch through the window also helps.