Because Dart is similar to JS, easy to learn, and better in regards to performance, tools and security. JS is a mess, just look at the equality operators and the fact that you can manipulate classes like String, etc...

The release version runs native code, so is faster and uses less power.

But RN also compiles to native code? How’s it different?

I don't know.

Seems like astro-turfing to me.

Dart isn't much better than JS (as TS or Reason are) so switching doesn't give you too much gains, but a smaller eco-system.

Also, the canvas approach of Flutter feels kinda backwards.

I think it's artifically hyped by Google.

React will be much simpler with hooks and the RN updates will improve native inter-op.

But yeah, that's just my take and I'm often wrong with predictions xD