Wow the second point, encrypting the files but providing transparent access for a while thereby corrupting even the backups is really scary.

Although maybe this would be detected when your incremental backups start saying that all the files have just changed. Some softwares will require manual action if more than x percent of the corpus needs to be resynched.

One option I don't see in the list, is just basic, file wiping, instead of encrypting. People are lucky there's even an option to unencrypt.

Worst ransomware ever: "pay us now that we have deleted your files or else !"

But why would you pay if there's no "hostage"?

I'm saying that a virus that wants only to destroy, instead of get paid, is more dangerous than a virus that wants paid. It's the difference between a kidnapping and a murder.

What's the incentive for such a virus ?

Do you not remember viruses in the 90s like the ILOVEYOU virus? Plenty of hackers wrote viruses that maliciously destroyed data just because they could.

Schadenfreude?