I personally always prefer to get a quick quote from an external insurance provider before accepting the airline's offer. In 90% of cases I save quite a bit and the coverage is more complete, especially for things like lost baggage, cancellation for personal reasons, or medical assistance. Airlines know perfectly well that people buy their insurance at checkout without thinking about it, so the prices are inflated.
One detail that a lot of people overlook: read carefully what the airline's insurance excludes. Many only cover delays if it's the airline's fault, not third parties'. And then there's the thing with pre-existing conditions - if you have a known medical condition, sometimes you're not covered. With external insurers you often find more favorable terms if you read the fine print properly. For a Milan-Rome flight the risk is genuinely low, but if you then need to catch a connection or have a particular situation, it might be worth having real protection.
Check if your credit card already covers cancellations, and in that case you can really skip it. If you don't have anything, take a look at Ucover, Hype or similar - spending 10-15 euros on a decent policy is different from paying 40-50 to the airline for the exact same service.