The problem is, typescript will still silently infer 'any' type in certain cases even with all the no-implicit-any compiler flags enabled, and you'll never know when this happens until you have a bug.

Not to mention that its type system is unsound by design, and not because of null. Typescript only pretends to be safe, so in practice you end up writing a lot of type annotations for very dubious gain.

Stricter options like Facebook Flow or Scala.js are way more useful.