> Is there then no pathway for actually fixing the bug?  aka how can I get `required=True` to be the default.

There may very well be but, unfortunately, dealing with this newly-identified 3.x compatibility issue takes precedence for 3.7.0.  In general, for cpython, all other things being equal, the status quo wins and, in this case, that means not breaking 3.6->3.7 compatibility without a good reason.

The underlying problem here, IMHO, is that we are essentially an all-volunteer project and at the moment argparse does not have an active core developer to review and champion change requests.  If a core developer does want to take up the existing queue of argparse issues, we *might* come to the conclusion that making another incompatible change is the overall right thing to do.  But, until that happens, the least bad option is to not make things worse.  How to get more core developer interest in argparse issues is a whole 'nother matter and out-of-scope for this issue.  Sorry, I wish I had a better answer.  Thanks, Anthony and everyone else here, for your input.