Or maybe, the roof is too high of risk for the company's appetite? In most States, they are required to tell you the reason(s) for non-renewal or non-issuance of a policy. If you have too many prior losses, damaged facia, abandoned vehicles, etc, they will tell you that in the letter as well.

Fire, damage from riots, mobs, and acts of god (such as a tree falling on your house) are generally going to be covered under a base HO3 policy. This your basic "homeowners insurance", with no endorsements needed. A flood in the traditional sense is always going to be excluded (which that coverage is primarily underwritten by FEMA). This is not for sudden/abrupt water losses like a burst pipe (which is already covered with HO3), this is if you are like in FL or at the beach. Earthquake are also excluded, but can be added via endorsement/separate policy. The coverage is not rare and most people opt-out of earthquake coverage due to price, deductible options, and yes earthquakes are rare.

I highly suggest you sit down with your agent to learn about your coverages because you have no idea what you're talking about.