It's easy to believe that there will (sooner or later) be a standalone implementation of arc. In that case, we don't want to tie the design of arc's module system (if any) to scheme's.
Also, do we want to integrate Arc as a language in DrScheme?
The release implements the Arc language in MzScheme. Using the MzScheme module system in the implementation of Arc doesn't imply anything about a future module system for the Arc language.
Worrying about future implementations at this point is my view a bit premature.
