There's a great series by Jensen Harris, Office Program Manager, about how they designed the Ribbon: https://blogs.msdn.microsoft.com/jensenh/2005/09/26/the-why-... (you can find the rest in his blog archives, unfortunately the images are gone)

It was an incredibly complex undertaking, Microsoft did many studies, had focus groups and the whole thing (Office after all, is a major business to them, worth billions of dollars).

The end result was demonstrably better for the vast majority of users (Microsoft had hard numbers to back their design decisions).

And yet if you read many of the comments on tech forums you'd think Microsoft killed the users' puppies.