You would be mad not to have travel insurance particularly if you were travelling to somwhere the USA. I know it is a bit fuzzy where you miss flights etc but where you really would need it is if something happens to you abroad e.g. an accident or sudden illness and you need to go to a hospital or even worse have to be repatriated home; you could be talking possibly in the region of hundreds of thousands of dollars, if you need lenghty hospital stay or surgery in somewhere like the USA