People tend to underestimate the value of a solution that folks, especially less technical folks, are already trained on, comfortable with, and one that is known to work as expected.
It was basically "if the US ever plays this card, all hell will break loose for their IT companies". So ICC and others simply assumed it would not happen.
That's a very simplistic view of what Microsoft offers. They don't sell an office software package but a very robust solution for running the software side of a business.
The OS, office package, email (server and client), calendar, cloud & backup, BI, etc. all aligned work almost seamlessly with each other (compared to the alternatives for sure).
Nothing on the market comes close and that is the reason they are worth trillions, not because they use closed formats.
I know how to use MS Office. All my colleagues know how to use MS Office. People want to solve their daily problems, not learn how to use new software.
The "weird" alternative you expended political capital to put everyone on works slightly differently or lacks a feature out of the box?: "What were you thinking?!"
I'm sure people get killed all the time for using American services. It's just that they were all brown "terrorists", not liberal Intitutions situated in Europe, until now that is.