They bought a service marketed as a privacy protection tool in order to monitor the traffic of its (largely unsuspecting) users, so they can know which startups to buy to prevent any competition or innovation.

Perhaps Facebook doesn't mind appearing blatantly creepy and evil, and is happy to continue to live off the unbothered and ignorant users, a la the Nigerian prince scams[0]?

[0] https://www.microsoft.com/en-us/research/publication/why-do-...

Wasn't it always?

It's not about what Facebook is doing, it's about how it's perceived. Many blame Facebook for the Brexit/Trump/ultra-right rise and see any step of the social media giant as evil. You know how they say...if a man connects lives of a billion people and fucks up one democracy, they don't call him a visionary, they call him evil.