-1 on moving this to builtin status.  For a long time, we've tried to keep a back pressure against adding more builtins (in part because it increases the learning curve for the core language).   The SimpleNamespace() type would need to become *much* more popular to warrant becoming a builtin (even then, other tools such as copy.copy() or collections.OrderedDict() would likely be able to make stronger claims).  AFAICT, the SimpleNamespace() class has been used exactly once is the standard library (in venv) and almost not at all in published code.  IMO, it is *very* far from warranting builtin status.