To be fair, youtube was forced to do so because of corporate, news/media and political pressure. People forget that youtube also fought against the DMCA and corporate/media pressure before they lost.
https://motherboard.vice.com/en_us/article/ezp4xa/youtube-is...
https://www.recode.net/2016/6/20/11974514/taylor-swift-youtu...
> Listening to the CEO of YouTube cry "but think of the content creators!" is about as transparently self-serving as a US politician crying "but think of the children!"
Of course it is self-serving. But it's also true. Youtube has been consistent in their support of fair use because as you pointed out, it's in their own self interest.
The problem for youtube is that content creators on youtube aren't organized or powerful like the media companies. And whatever you think, they have to follow the law and like most companies, they are going to err on the side of caution when they are forced to.