Comment by skribanto

Well, it can make some chained function composition easier.

  Ick1 result1 = potentiallyNull1();
  Ick2 result2 = (result1 == null) ? null : potentiallyNull2(result1);
  Ick3 result3 = (result2 == null) ? null : potentiallyNull3(result2);

vs

  Ick3 result3 = potentiallyNone1()
    .flatMap(potentiallyNone2)
    .flatMap(potentiallyNone3);

You could maybe move the null check inside the method in the former and it cleans it up a bit, but in the latter you can have methods that are explicitly marked as taking NonNull in their type signature which is nice.