You don't have to be an admin on Windows, but you can't do anything if you aren't. At every company that hires me where I have to use their PC, one of the first steps is always to request admin rights, because I need to be able to install dev tools. On Linux, you can have a special user account that can only install apps, without requiring root access. I think that would go a long way to preventing this sort of ransomware.

Although losing data on a user machine should of course never be crippling to a company in the first place. Make sure everything is committed to a central location, as well as backed up at regular times.