Pond, it does not matter what they were designed to do, does it? The issue is what could be done with it.
This does not only occur with guns. For example, those who own swimming pools are often required to build fences around their pools, to prevent trespassers from falling in and drowning.
Personally, I would like to see laws passed that specifically barred people (or their estates) from being allowed to even file a lawsuit for damages sustained during the claimant's (or the deceased's) commission of a crime.
I don't think swimming pool owners should have to build fortresses, nor do I think gun owners should be held responsible for the criminal actions of others.
Again, I recommend the use of safes and lockboxes. I recommend any number of things; I do not think they should be mandated, however.
Edit: Going back to the car analogy - when was the last time you saw a media uproar because somebody left his car keys on a wall hook near the door?