[pron]

I think that while backwards compatibility has always been a very important concern of Java's (as it should for such a popular language), this is also a matter of philosophy. Java's maintainers know that every feature comes at a price (of complicating the language), so the first consideration is always whether the feature provides enough benefit to justify its cost. The second consideration is whether the feature conforms with Java's "spirit" as a "blue-collar" language, designed for use on multi-MLOC projects, possibly worked on by hundreds of developers. Such a language has different requirements and a different "feel" from languages designed for quick development and comparatively small teams.

Obviously, at this stage Java has accumulated quite a lot of baggage, as could be expected from such a mature and ubiquitous language. Some of these issues are addressed in Java 8, and some by other JVM languages with various degrees of adherence to the Java philosophy.

I would strongly recommend watching these two talks by Joshua Bloch, where he explains Java's goals, philosophy and design. These goals were later adopted by Google for their own new languages, Dart and Go, that have the same "Java feel":

* http://parleys.com/play/514892250364bc17fc56bb15/chapter11/a...

* http://parleys.com/play/514892290364bc17fc56c444/chapter0/ab...