One reason got Google+ to want your location is to know who is nearby. That isn’t really an issue for those who only access Google_ from their home computer, but those of us with smartphones are a different matter.
Check your privacy settings to see who other than Google can see your whereabouts. If you have them set right, then the tracking isn’t really an issue since the only people who know are Google and those who have other means to track you anyways, often law enforcement of some form or another.
As for why people are not paranoid about advertising the fact that they are not home, think about it for a moment. I don’t know about you, but I have a job, so it’s a pretty good bet that I won’t be home during the day five days a week, and that was considered “common sense” long before the Internet hit the mainstream. As for random people, odds are that anybody who wants to break into my house probably isn’t tracking my phone and/or is close enough to my place to see whether I am home or not anyways.