Do burglars wander the streets at night testing doors of random places to see if they're locked? If we put the issue to cars instead of houses, there are a lot of people who would rather have their stereo stolen than have their stereo stolen and window broken. To me most locks are more peace-of-mind security.
I just don't buy that lacking some form of security dooms you to whatever penalties the security may have protected against, if indeed any.
I had my car robbed a few weeks ago, they took a 4 year old GPS and $2 in change.
I still feel wronged (it's a little annoying) but I still don't lock my doors (the amortized cost seems to be about $15/year where I tend to park. It's 99% about the time/money trade-off and 1% about what's morally right.
I just don't buy that lacking some form of security dooms you to whatever penalties the security may have protected against, if indeed any.