The bad thing is that they killed compound objects, so every java program creates huge numbers of small dynamically allocated objects.

You can't create a struct containing objects - just a struct containing pointers (in this cased called references) to objects.

You can't create an array of objects. Just an array of pointers (references) to objects.

So a java program always creates a huge pressure on the garbage collector. Even quite trivial java applications can quickly have walked through 50MB of objects that needs to be reclaimed.

By the way - java did introduce the interface keyword. But the concept is just as possible to use in C++ too by having accessor functions return helper classes representing the interfaces.