The cost of adding separate motion sensors for occupancy is not worth it and overkill for a home. Also, not integrating some security functions with my z-wave locks makes life too inconvenient.
Yes, if someone spoofed a mac id and broke my WAP2 encryption on my wireless network, I'd be doomed. They could also hack my 10 character username and 12 digit password to my VPN and I'd be doomed. If they had a z-sniffer (costs thousands of dollars) and figured out how into break my z-wave secure network (yes it is actually secure, locks use encryption, while traditional z-wave devices do not), plus figured out my eight digit pass code to work my locks, I'd be doomed. Notice in the article they don't even discern between secure z-wave devices and traditional ones? That's because the writer doesn't even know what they're talking about. Everyone knows that secure z-wave devices can't even talk to non-secure (traditional) z-wave devices.
In all, who cares though. If someone really wants in, isn't it just easier and faster to hop a fence and break in my back door? What do you think a burglar is really going to do? Stay outside my house in an unmarked van for 12 hours trying to break my networks encryption? I think not. That would arise even more suspicion than just quietly coming in through my back door.