On top of that, there was the removal of built-in J2EE; you needed to add external copies of the J2EE pieces, and some of them (like CORBA) weren't available as separate packages. And later versions of these external J2EE packages changed the namespace of all their classes, which is especially painful in Java due to its common use of dynamic loading of classes by name and lazy linking (and lazy linking errors do not inherit from Exception, which allows them to escape from catch-all "catch (Exception e)" clauses). The rest of the ecosystem is starting to depend on these new versions, so staying with old versions of these J2EE packages is not an option.

The fact that Sun never removed any deprecated methods even after they were proven dangerous was a sticking point that generated friction between coworkers over new code using deprecated functionality.