Exactly like React - means the language will be abandoned by wider community. The Facebook peeps are gradually building themselves into corporate self-invented mono-culture.
React has managed to bring together people in C#, Python, Ruby, and Erlang to name a few languages... who all previously used different frameworks, or just jQuery.
/sarcasm
It gives you more rights. Full stop, end of story.
This is a multi horse race and even if you are not scared of patents it might be unwise to bet on the horse you think will scare other people. (Case in point, Wordpress.)
Fact of the matter is, it's just posturing. Software patents are utter bullshit and the facebook license clause reflects this.