Hi Greg,
I believe you are right: the Request Subject becomes the Issue Name, which is a required field, and if converted, the Task/Project Name.
Intended as a short, unique reference (given Workfront's helpdesk roots), it's easiest to pick a simple convention (whether educate the "as designed" intent, something simple like the raiser's initials and datetime, a dash, etc.) and train users accordingly.
That said, if that still seems irksome, I think at one point I knew of a way to at least default a value so people could skip it; try adding "&subject=n/a" to the url if you are curious.
Regards,
Doug