Yes, travel insurance is worth carrying for a trip to Guatemala City, and the honest reasons here span care quality, real geological risk, and the value of checking current conditions before you travel. Guatemala's capital generally has better-regarded private hospital care than much of the country, though care quality still varies by facility, and a policy that pays providers directly spares you from navigating an unfamiliar private-care system out of pocket during an emergency, rather than fronting costs and waiting on reimbursement afterward.
Guatemala sits in a genuinely active seismic and volcanic zone - the country has a real history of damaging earthquakes, and active volcanoes including Volcan de Fuego near Antigua have produced fatal eruptions in recent years. Confirm your policy covers medical evacuation and treatment linked to natural-hazard events, and check current government travel guidance for volcanic activity before finalizing plans near Antigua or Pacaya, since conditions can change with little warning and local access rules can shift accordingly.
Hiking near Pacaya volcano, a popular day trip from the capital, and general active tourism around Antigua are genuine draws that carry real risk given the volcanic terrain involved. Confirm your policy names hiking and volcanic-area excursions specifically, since some general policies treat this kind of activity differently from routine sightseeing. It is also worth checking current government travel advisories for Guatemala more broadly before you travel, since security conditions can vary by area and change over time.
Keep any clinic or hospital invoices, since private facilities generally issue standard paperwork on request, along with any tour-operator incident reports from volcano excursions. Many policies require prompt notice before non-emergency treatment or evacuation is arranged, so check your policy's claims process and confirm whether it settles directly with providers before you rely on out-of-pocket payment in an unfamiliar system this far from home.