I like the type hints. The're not perfect and they've changed a lot between versions, but they really help catch issues early that you'd usually need to write unit tests for. Adding type hints is easier than writing those unit tests.
Then you can focus your tests on more interesting things
You just need to set your build up to actually do the checking as type hints by default are just documentation
My main complaint about them is no first-party support for type checking, you need external packages like beartype decorators.
Yeah, it would have been much better to have them be default enforces if present. Keeping them optional is fine, but I don't get the use-case for "you can add them but not check them"... that just leads to actively misleading hints