OP might mean "laptop" instead of computer. Or more specifically, laptop that is regularly taken out of the home.

I'm with you. If someone wanted to steal any of my computers, they'd have to break into my house. Possible, but also statistically unlikely, as I live in a reasonably safe community and lock my doors. I don't see the benefit of full disk encryption on a bunch of computers I keep in my home. For the special case of a laptop that is frequently taken out of the home and used in public, where thieves might be? Sure, encrypt it.