I have bash CGI scripts too, though Shellshock and bash's general bug-proneness make me doubt that this was wise.
There are some advantages of having the CGI protocol implemented in a library. There are common input-handling bugs the library can avoid, it means that simple CGI programs can be really simple, and it lets you switch away from CGI when desired.
That said, XSS was a huge problem with really simple CGI programs, and an HTML output library that avoids that by default is more important than the input parsing—another thing absent from Python's standard library but done right by Django.
As mentioned elsewhere in the thread, the query parameter parsing is still in the Python standard library, just invoked differently.