Many people fail to see that the real benefit of using TypeScript is better tooling (code completion, intenseness, refactoring capabilities, self-documenting code) and not the mere ability to catch some stupid runtime errors at compile time.
Just as yanis_t said, they're easily worth it even if you ignore the significant bug reduction (approximately 15%).
I don't know of any other way to get that kind of productivity boost. What would you suggest instead?
It is absolutely a unique feature of typed languages.
Because if that was the only benefit typescript had, it would be a win. I mean that was the whole point with JSDOC.
Anything that shortens the feedback loop from writing the code to seeing if it works is a win.
This is the equivalent of saying, "I see many people switching jobs for no reason other than to make more money". Like... That's the not the only reason but it's a big one.
Then you get into algebraic data types, and encoding logic constraints into the type system, and you can make entire classes of bugs impossible to write.
Type systems are about safety and productivity.