I struggle with this one because exceptions are a perfectly good solution. The compiler will tell you when you are not handling a failure case. And if exceptions are unchecked, then you won't get a compiler warning but at least failures will be obvious at runtime.

Why push java towards this 'failures as return values' when we already have a solution? Yes, you will be able to get the compile-time safety by immediately using switch on the return value, but what if you don't? Exceptions are a completely sound solution, failures as return values can easily escape detection.

No-one likes having to think about the error cases, it feels like it complicates things. But we need to stop seeing exceptions/try/catch as something to eliminate and realise that this approach is one of the best innovations of Java. Using return values, or monadic approaches to error handling, are fundamentally unsafe when you have a mixed paradigm language. Far too easy for the programmer to do something wrong, so we're relying on discipline again and not the compiler. In other words, back to square one.