All the existing code and libraries have to be recompiled. Non-javac compilers have to be updated, etc. Pretty much all byte code editing tools would be obsole

All the existing code and libraries have to be recompiled. Non-javac compilers have to be updated, etc. Pretty much all byte code editing tools would be obsolete as the constant pool needs change and so on. Also the generated byte code would be more verbose (worse load times) The current change is easy to implement and it'd work on code compiled for/with java 1.0.