However, if you want to use e.g. TypeScript with React, than this is a very big thing! Up until now, it was always a bit of a hassle, and with this change, it's completely straightforward (especially if you don't want JSX). You'll also need propTypes less because you can just use TypeScript interfaces for the `props` constructor parameter. Plus, TypeScript already has property initializers and all that, so all the other annoyances that you get when doing this with plain ES6 classes disappear with TypeScript.
I'm currently really considering porting my current project back to TypeScript for this single reason. The bad mix of TypeScript and JSX is what mostly holds me back. I'd like my view code to be somewhat understandable/hackable by designers and JSX really matters there. Any suggestions?