If they've left the house deciding to commit murder or rob someone, sure. However, I think it would make a difference in other situations... for instance, when someone's just out and about, gets into an argument, and things escalate.If someone had ulterior motive, they would hide it regardless of legalities.
All of those things demonstrably reduce risk. Most of the time, a firearm demonstrably increases risk.Are people who wear helmets when riding their bike, or wear a seat belt when driving their car, keep a first-aid kit handy, or keep a fire extinguisher in their home paranoid? People don't do these things expecting to be in an accident or have a fire, yet no one with any sense would suggest that these cautionary practices are unreasonable.
And if someone had a halon fire extinguisher (i.e. one of the types that works by removing oxygen from the air, so it has the potential to asphyxiate people in the immediate area) to "protect" their home, I think I would question how reasonable their decision was.