I've gone back in and tried editing another pre-1700 profile. This time, I simply ignored the banner which said I was required to go to the form, if I wasn't coordinating with a project on this edit. It worked: minor edit successfully saved. (Lesson wryly noted: Scofflaws have a point.)
Jillaine, I did this before your reassurances arrived, on the basis of a comment on the discussion Danielle linked for us, but I appreciate your confirmation.
Danielle, you make a good point: How useful is this form, if it can be so easily ignored? It's only going to catch us mildly OCD types, who actually believe they need to comply when something says compliance is required, and who are probably following project guidelines on our edits, anyway.
Helen, as you were, I was caught by the form-loop because I'm almost never actively coordinating with a project on my edits. I do try to be aware of and comply with project guidelines when I'm operating within a project's known territory, and I do formally belong to several projects. But I'm more of an active lurker than a coordinating participant. As you can undoubtedly see from my initial reaction, I sympathize entirely with your doubts about continuing.
As I said before, I can see a real use for this form, if it could be made into a gateway (or sentry post) for proposed edits to an actual project-protected profile when the proposer hasn't been pre-cleared by the project. Blocking gedcoms from making edits or attachments to PPPs would be separate. I don't know how complicated it would be to modify the project badge so that it would pre-clear someone to bypass the form, much as the pre-1700 or pre-1500 badges seem to work.