Although I'm happy without it, I would find that interesting as well. I think there are ways to have part of a sign-up draw on a specific tag set, and part of it allow truly free text or to draw on the whole Archive, so it might not be necessary to have the characters nominated in order for people to be able to input them in a character field of the sign-up form.

In any exchange where parts of the sign-up field are optional, someone will misunderstand and be annoyed to receive a work that does not use those optional details. But I guess that's a problem that can be worked around or tackled on a case-by-case basis (and up to mods to decide how much of a headache it is).