If the trip is not expensive or in a local vicinity then travel insurance is most likely not required, but for the more expensive domestic locations and international travel requiring money, time, and planning saving a few dollars on insurance is not worth the regret or risk.
Being in a foreign country can also be completely unfamiliar for a tourist and the local surroundings and trapdoors that can snare tourists unacquainted to it, can prove costly. Insurance provides most importantly, peace of mind and this will make the trip more enjoyable.