I'm not sure if I'm following your point. Are you suggesting that anonymous inner classes aren't useful in a well-designed Java program? If so, I'd have to disagree.
As an example, the Java Collections API (one of the most well-designed Java APIs, imho) uses Comparators extensively. It's pretty common to define the Comparator as an anonymous inner class when you need to do a one-off sort() or max() call.
Scala just makes it easier to use this pattern. There's no need to go through the effort of wrapping the function in class if you're only going to use it once.
As an example, the Java Collections API (one of the most well-designed Java APIs, imho) uses Comparators extensively. It's pretty common to define the Comparator as an anonymous inner class when you need to do a one-off sort() or max() call.
Scala just makes it easier to use this pattern. There's no need to go through the effort of wrapping the function in class if you're only going to use it once.