Yes, travel insurance is still worth carrying for a trip to Bilbao, even though it is one of the lower-risk destinations in this guide. Spain's Basque coast has well-developed hospital care by regional standards, so the honest case for coverage here is less about danger and more about cost, trip delay, and the gaps that even good local care can leave for a visitor from outside the EU, and a policy still smooths over lost luggage, cancelled flights, or an unexpected pharmacy run in a country whose systems are unfamiliar.
Bilbao itself has solid city hospital care, and the wider Basque coast is generally well served for a European destination. What a policy actually needs to cover is the uncertainty around your own arrangements: check whether your existing health cover extends abroad and specifically to Spain before you travel, since coverage rules differ by country of residence and by plan, and the page cannot tell you what your own policy or national scheme includes.
Most visitors come for the Guggenheim Bilbao and the wider Basque coast, and the practical risk here is more logistical than medical - the Bay of Biscay can bring rough Atlantic weather and coastal storms in autumn and winter, disrupting ferries, flights, and outdoor plans along the coast. The city itself poses little unusual risk beyond normal urban travel. Trip-delay and cancellation cover is worth checking for a shoulder-season visit built around coastal excursions.
Keep receipts and any clinic paperwork if you do need treatment, and check your policy's documentation requirements before relying on memory later - Spanish providers, like most in the EU, will issue standard invoices and reports on request. Many policies also want notice before non-emergency treatment is booked, so check the claims process in the wording rather than assuming automatic reimbursement once you are back home.