This seems entirely reasonable to me.

I guess the generalization of this would be for the Perl Run-time system (the Bytecode interpreter or Parrot or whatever) to recognize when a routine is being called in a void context and to propagate down to all callees to not bother assigning to or otherwise generating any data structure that is to be returned, unless that data structure is needed for other processing.

It also might simplify Perl to then define foreach in terms of map, etc.