The else doesn't need to be there. The $smtp is still going to need to be created in the same way (or at least it seems so to me).

Key term here is need. Yes you are correct it doesnt need to be there, but the idea I had was that this extension is not only going to cover the case of authentication. One thing I would like to do is implement smart hosts. The user should be a able to supply a list of SMTP hosts and have MIME::Lite cycle through them until it manages to send its mail. So for what I have in mind keeping the simple case seperate from the more complex case makes sense.

Placing the change inside of Net::SMTP makes more sense in that it keeps the logic in the right problem space and thereby making it benefical to a larger user base.

Agreed. However I think you may be waiting a while before such a patch is implemented. Probably longer than it will take to go into MIME::Lite. If MIME::Lite does its own ting, and then sometime down the path Net::SMTP is altered as you say then MIME::Lite can be modified accordingly. Until that day Id rather think about what is directly under my control than what would be possible when a patch is applied to a module I have no control over.