Hi Shaun, no you're not doing anything wrong, that's just how the Offset function works - the offset function in the geometry library happens to build a quite dense result.

The whole process of doing an offset involves a kind of fitting process that marches along the curve, with NURBS curves you cannot just offset existing control points to make an actual accurate offset curve. See this previous discussion for some more information:
http://moi3d.com/forum/index.php?webtag=MOI&msg=3838.21

And like Ed mentions, you can use the Rebuild command to simplify the complex offset result to get something more manageable for control point editing:
http://moi3d.com/2.0/docs/moi_command_reference10.htm#rebuild

Probably in the future that rebuild step will happen automatically, I just need to ensure that it maintains the same level of accuracy in the result.

- Michael