My reason for the post was to suggest people check their water stainer, not to start a dialog about closing seacocks. My failure was due to metal fatigue, something you normally wouldn't see unless you were looking for it.
Sorry, but your experience is a very good case for closing them, IMO. You may want to run the risk to save a time on each trip, but you could have lost your boat.
I don't own a boat (don't get to sail enough), but would go through a pre-cruise checklist before each outing even for my own boat. That would include the position of seacocks.