I have been using React to build frontends for about 6 months now and I love it. Should I learn Angular2 instead and ditch React because of its sketchy licensing?
It depends. Does React's license cause problems for you personally, or for your employer or clients? If so, that would be a good reason to avoid using it.
I'd suggest giving Angular 2 a try regardless. It's pretty well thought out, and you might find that a lot of things you need a separate library for are included with A2. It isn't excessively opinionated, though. You can easily plug in tools you use with React (such as Redux) and they work nicely with Angular 2.
If you're only using React with ES6/ES2015, you could also try Preact. I've found it to be a pretty decent drop-in replacement for React. There's also a preact-compat package that supports some additional React features.
You bring up a good point. The biggest point of using React for me was using React-Native which Preact doesn't seem to have. I could definitely use Preact for most of my projects as I really only use React for its ability to make front-end components with ES6, so I will have to look in more detail. Thanks for the reference.
You're welcome. You're correct that there's no React Native equivalent for Preact.
That might be a point in favor of Angular 2 where you need code that can be shared between mobile and web apps. Nativescript is similar to React Native, and has built in support for Angular 2.
I'm not one of a bandwagon jumper, but I have been hearing similarly nice things about Angular 2 being equally as un-opinionated as React in many ways. I just hate losing the momentum that I currently have with React/Rails apps.