Hi, 

I have been wanting this feature for quite a long time. IMHO, binaries and scripts should always include a man page. The Debian developers require that. However, man pages have a 'bizarre' format. 
Long talk, short time. I did implement something. I tested it on Python 2.7 since my project currently only supports Python 2.7. 
I think it should not be complicated to port to Python 3.X. 

I doubt if the correct place for formatting a man page should be in argparse.py itself. My solution is an extension of Andial's brecht solution that uses ofcourse argparse.

You can see it in action in https://github.com/pwman3/pwman3

I am also attaching the code here. 

I hope you will find this file useful. I would appreciate your comments too. 

Regards, 
Oz