Since many C applications take argv as a (char **) it seems reasonable for python to keep a function for the C api that accepts a (char **) argument for argv.
I'm not quite sure what you are suggesting: either that there is a function in the C API that accepts a (char**), or that PySys_SetArgv be that function.
The latter alternative is out of question, as it breaks the Windows port of Python - there is simply no way of representing argv with char** in a meaningful way. It also breaks backwards compatibility.
As for creating another function: please provide a patch to bugs.python.org. I believe this patch is *very* difficult to implement, unless the function can accept some severe limitations.