Yes, travel insurance is close to essential for a trip to Fitiuta on Ta'u, the remotest inhabited island of American Samoa's Manu'a group. The honest core of the answer is evacuation logistics rather than any dramatic on-the-ground danger: this is a small, isolated village reached by small aircraft or boat from the main island of Tutuila, and local medical services are minimal by any standard. Visitors typically come for the National Park of American Samoa's Ta'u unit, hiking near Lata Mountain, or genuinely remote reef diving and snorkeling.
Serious cases on Ta'u are stabilized locally if at all possible and then flown to the Lyndon B. Johnson Tropical Medical Center in Pago Pago, the territory's main hospital on Tutuila, with anything requiring higher-level care typically transferred onward to Honolulu. Confirm your policy explicitly covers inter-island medical evacuation and international transfer, since a policy that only reimburses local treatment misses the part of the risk that genuinely matters on an island this remote.
Hiking to Lata Mountain within the National Park unit and reef diving or snorkeling around Ta'u are real draws, and both carry meaningful risk given how far this village sits from any emergency service. Confirm your policy names hiking and diving specifically, and keep in mind that American Samoa, like the wider South Pacific, sits within the cyclone belt roughly November through April, when inter-island transport can be disrupted with little warning.
Keep any clinic paperwork, park-service or dive-operator incident reports, and receipts for emergency transport, since documentation is genuinely hard to gather and easy to lose on an island this small and remote. Many policies require prompt notice before an evacuation or major treatment cost is incurred, so review your policy's claims process well before you travel rather than after you are already on Ta'u with limited communication back to civilization.