When everything is terrorism, nothing is terrorism.
What? No, that's not the logical solution. Have you considered the consequences of paying that money beyond the immediate deaths? You've suddenly put a real price on terrorist attacks - as in, if I decide to go through with a terrorist attack after 9/11, I know that I can extort the country for anywhere up to $100m. Hell, everybody with a grudge against the US suddenly has massive financial incentive to carry out attacks against the US. How many more people will die because you've decided that it's okay to pay terrorists?
There are plenty of people with a grudge against the US, some of them quite rich. US foreign policy made sure of that. Extra 100 million would make no real difference. The thing stopping them is distance to US and threat of deadly force.
Yes, there are many reasons. You seem to adopt a highly deontological ethical stance. But in actual decision making, being pragmatic, showing some grace by being human and making hard compromises, and at the same time being utilitarian are often more rewarding. For example, governments all over the world have (often secretly) paid ransom money for kidnapped citizens. If they couldn't do that any longer, because it is illegal, then that would doom the fate of many kidnapped citizens.
Elected officials should make reasonable decisions that minimize harm and costs and should be willing to make compromises, not brag with their iron fist policies no matter what the consequences are. (That's just my personal opinion, of course.)
> After all paying a ransom is very literally funding terrorism
Do you have any proof for that claim? If not, then you are merely watering down the meaning of the word "terrorism". AFAIK, these ransomware attacks are conducted by ordinary criminals, not by terrorists.