This might not be as trivial as you'd imagine. For example, a module might pull in some unsafe hashing algorithm module (like MD5) dynamically when asked to do so or as fallback option. Depending on a lot of circumstances, this might be a huge security problem (passwords without salt) or it might be OK to do so in support of some nonsecurity-related legacy requirement. And in the case of your application, it might not even load the module, just require it to be installed "just in case".
perl -e 'use MIME::Base64; print decode_base64("4pmsIE5ldmVyIGdvbm5hIGdpdmUgeW91IHVwCiAgTmV2ZXIgZ29ubmEgbGV0IHlvdSBkb3duLi4uIOKZqwo=");'