Yes, travel insurance is worth having for a resort trip to Hamilton Island, and the reason has less to do with the island's polish than with what surrounds it. Hamilton sits within the Whitsundays, a stretch of reef and open water off the Queensland coast that brings its own genuine risks - diving, sailing, and a real cyclone season - regardless of how comfortable the resort itself feels. The resort setting can make it easy to forget that Hamilton Island is still an island with limited services of its own.
Diving, snorkeling, and yacht sailing around the Whitsundays and the wider Great Barrier Reef are the main draws for most visitors, and all three carry real risk that a generic travel policy sometimes underinsures - dive-depth limits and sailing or crewing exclusions are common. Confirm your policy names diving and sailing specifically, and check any depth cap, before booking reef excursions or a bareboat charter. Even a single introductory dive or a day-sail booked through the resort counts, so check the fine print rather than assuming a package trip is automatically covered.
Cyclone season, roughly November through April, is a genuine consideration for this stretch of coast, and storms can disrupt flights, ferries between the mainland and the island, and reef excursions with little notice. Trip-delay and cancellation cover is worth checking closely if your visit falls within this window, since resort bookings and charter schedules do not always allow easy rebooking.
Hamilton Island has a small medical center for routine care, but anything serious is typically stabilized there and then transferred to a larger hospital in Mackay or Townsville on the mainland, with further specialist care available in Brisbane if needed. Confirm your policy covers medical transport off the island, since that transfer - not the resort stay itself - is the part most likely to involve real distance. Check this cover before traveling rather than assuming on-site facilities suffice.