I don't think every language needs to be rigid - something like TypeScript's gradual, unsound typing can be very valuable, and I certainly think there's a place for a language where casting is easy and idiomatic. But you can do that and still enable generics, covariance and the like - as TypeScript in fact does.

What's incredibly infuriating to see a language that clearly has everything it needs to offer generics - indeed it clearly has a generics implementation already written, since the builtin types are generic - but it won't let me use them.