I agree with you on most points, landlords are inherently being paid for assuming risk. I believe what is unfair about the situation is that some of the risk they are supposed to assume is actually carried by government programs. The tenants are paying taxes that the landlord benefits from as a form of insurance (risk mitigation) while the tenant does not. This is a form of wealth redistribution in which the landlords benefit.
A prime example is flood, just like you said. FEMA has historically stepped in to mitigate that financial risk. The tenants' taxes essentially pay for "federal flood insurance" for the landlord.