This is a major question that people ask themselves all the time while booking travel. The choice is ultimately up to you but there are a few things to keep in mind. Many health insurance carriers will not cover you when leaving the country (here in the USA). I have heard horror stories about people injured on their trip and needing a life flight back to the states causing them to be in debt of over $200,000. Yes, those cases are VERY extreme and VERY rare but are a possibility. Luggage can be lost, wallets can be stolen. Here in the Northeast, everyone wants to leave in the middle of the winter freeze but sometimes, the snow is too bad for planes to take off, making people late for a cruise or tour. There are many different reasons to consider the additional insurance.
One recommendation I can make is to check what your current insurance (both home and health) will cover and then look into the fine print of purchasing additional travel insurance. Pre-existing conditions may not be covered so make sure you know what you are buying. Travelex created a great video below that does a good job of laying out different situations of what they cover. They are a reliable company that we often use at our agency.
Let us know if you have any questions!