I think this feature is essential. For the first step, I could live with it if I could specify a Project (in the Project:Subproject:SubSubProject syntax) for different mail drop addresses. That would not need any specific parsing, imho (other than looking if the project exists and if not dropping it into the inbox.
I would not need parsing of the subject or anything more than that, to be honest (for the first step). In a second step a default due date (+7 days, +1month), for example would be nice.
Alternatively something like maildropadr+project:firstname.lastname@example.org would be useful. Right now I send my mails (BCC) to email@example.com and to omnisync and try to work through everything manually which is not what I have omnifocus for.