Have used subways all my life but the last few years have dodged them like the plague. When I am in London I use the taxi and not the tube. Will rather spend extra knowing I am not trapped like a rat when something goes down. Next time I am back there i may use them again . It all depends on what is happening around the world with the extremist nutters.
I take the 'if it is my time, it is my time' approach. But, I life in Finland where essentially nothing is allowed to kill you by law, accidental or not. Except for drinking, they encourage that.