A country that pays ransom puts a bull's eye on the back of every one their nationals.
ISIS asks insane ransoms, $50M for a hostage or more. Then when the government official talks them down to $500K and claims to have saved 99% of the money, everyone feels good - except the next hostage. I'd rather take ISIS at their word. If they demand $50M, we deliver $50M in 500 pound bombs, or in ammo from a gunship.