> potential runtime errors (...) before they (...) happen in production

I seriously can't think of an example of this. If all testing is done properly, from unit testing to integration, etc, the compile time safety for front end development is just a nuisance. Runtime errors will happen, that's what tests and error tracking are for.

To put it differently, are all of these reasons that you cited worth turning this:

// ==========

import React from 'react';

const Welcome = ({ name }) => <h1>Hello, {name}</h1>;

// ==========

into this?

// ==========

import * as React from 'react';

interface WelcomeProps { name: string }

const Welcome: React.SFC<WelcomeProps> = ({ name }) => <h1>Hello, {name}</h1>;

// ==========

In the second example, gone are the years of making Javascript an elegant and straightforward language, adorned by the intuitive syntactic sugar that is JSX.