when tying to register a (primary) nodetype that does not extend from nt:base the following error is
"all primary node types except nt:base itself must be (directly or indirectly) derived from nt:base"
since the registry is able to detect this error, it would be easy to auto-subtype all nodetypes from nt:base. imo it's pointless to explzitely add the nt:base to every supperclass set. as an analogy, you don't need to 'extend from java.lang.Object' explicitely - the compiler does that automatically for your.