I don't think the whole concept of checked exceptions isn't a mistake, although the way they're implemented certainly is. In my experience, the problems with them almost always stem from one of two issues:

1. Built-in exceptions that are checked but should be unchecked, IOException being the main offender (I don't mean things like FileNotFoundException; I mean the kind you can get if the OS returns -EIO)

2. Lack of exception polymorphism, preventing you from doing things like l.stream().filter(SomeClass::somePredicateThatMayThrow), even if the function that you're doing it from can throw the same exception that the predicate can

I think checked exceptions would be great and nobody would hate them if those two problems were fixed.