I personally didn't have an issue with the BSD+Patents license--I think it's fine that they wanted to deal with patent trolls more easily. If you actually ended up in court against Facebook, you'd be in a better spot using React and it doesn't mean that you'd have to rewrite your whole app. There's an article from a patent attorney that explained some great points. I also talked about this on my podcast.
Having said that, other open source projects like WordPress were forced to move away from React due to not wanting to force their users to agree to the same license. I understand that there's still some fear that prevents people from using React. The MIT license switch makes it where practically anyone can now use React unless they just don't like the library. Which is a huge win for Facebook and the React community.