The Java people have always been very reluctant to add new features because they wanted to keep the language clean and simple, a design choice that personally I think is superior to 'rich' grammars like that of C++, Python, and C#. How many people really know and use 100% of the C++ syntax these days? Many companies actively enforce a strict subset of the language, and who even cares about C++0x? In my humble opinion C# pretty much jumped the shark when they started adding things like partial classes.
There's lots of things wrong with Java, but I think a worthy successor should at least keep that 'less is more' mentality.