> My first impression was that the 128-bit identifier kind of clutters the MBean view in JConsole (et. al.),
We shouldn't lose sight of the fact that Derby's MBeans are there to provide a management and monitoring api for Derby through a standard mechanism (JMX).
Jconsole is just one way of providing a GUI to manipulate these MBeans and is just a general purpose tool, so we shouldn't get too caught up on how they appear in it.
Applications that using Derby are unlikely to show direct representations of the MBeans, instead just making calls to their api attributes and operations. Those applications do need a way of ensuring they are calling the MBean for the correct Derby system, that's really what the system identifier is for, especially in the future when it may be more typical to support multiple derby instances in a jvm, with the possibility of some of those being "old 10.4" versions.