Most consumers will take risks like these seriously. If Bitcoin is going to go mainstream, it needs to address these concerns.

No one is going to strap a bomb onto you and then force you to wire them money. Remember, if someone were to do that, they would be caught immediately, because it's very easy to trace money transfers from banks. But Bitcoin makes tracing money impossible, thanks to mixers. That's why banks are safer than Bitcoin: A robber can't extract money from a bank without getting caught, but a robber can empty your brainwallet in a way that hides where the money has gone.

As for holding a loved one hostage, kidnapping for money hasn't worked for a long time. The failure rate for kidnappers demanding money is around 100% in the US. But kidnapping will become much more lucrative if Bitcoin catches on in the way you're imagining. It needs consumer protections.

Once bitcoin has consumer protections, it will be very valuable. That's why I'm advocating the protections. It's a necessary step in Bitcoin's development.

EDIT: To put it another way, instances of kidnapping and theft are rare because the current system defends against them, not because they're inherently rare. If bitcoin catches on without protections afforded by banks, then kidnapping and theft will likely become more common, because those tactics will be lucrative again.