[lmm]

I very rarely want to explicitly use an Optional<Optional<T>>. But every day I write code that works with a generic Option[A] and I want to not have to worry about what happens if someone calls it with A=Option[B]. I also frequently use Option as a parameter to some other datastructure like Kleisli or WriterT, which only works because it's an ordinary datatype that behaves like any other.

You say "you can just use the Optional class from the Java 8 standard library", but as far as I can see porting code that was written to use nullables would be a pretty big refactor, and there's no way at all to write generic code that works with both, so you'd end up having to maintain two parallel copies of your common functions.

Efforts to improve the performance of Option are of course to be applauded, but for a lot of use cases we're talking about the difference between (say) 50x faster than Ruby and 40x faster than Ruby. Scala is more than fast enough for a huge range of use cases; I don't think I've ever seen someone port code off Scala because the runtime performance wasn't good enough.