@hengiesel has talked about this in the following thread:
He’d like to implement a default setting (e.g. set in the Fields dialog), which would persist between sessions, but gets reset to its default when you have manually toggled it within a session (i.e. while adding cards) and then reopen the editor.
So far, he hasn’t gotten around to it, but it is on the roadmap.
TBH, I feel that quite a number of these decisions could be simply put in the preferences, instead of making a single decision for all users, that may not fit everyone. In both cases, you have to implement the new behavior, but if you put in the preferences a way to go back to how it was before, you also keep the previous version, so it should not require too much extra work.
I know, different people would have different ‘penchants’; for me, I’d be happy if the exact behaviour of above mentioned add-on could be duplicated; i.e. I do NOT want to have to RE-collapse unnecessary fields that I’m not going to enter anything into during this session, and which clutter the editor.
(No, I can’t delete these fields; there are needed occasionally.)