Support for other kind of default subjects

Both A) and B) can be achieved with theming.

really not following...
how it's supposed to be achieved with theming?
why couldn't "Re:" be achieved with theming as well?

I still think that all three of your use cases (numeric, author, date) can and should be implemented through theming. I am open to discussion though

Well, as stated before, I don't see how theming would sort this out. And, if so, why couldn't "Re:" be sorted as well through theming?
I just started to develop my first theme, so I'm pretty much a newbie. Please, alight me.

OTH, there is always the argument than configuration could be preferably than theming.
quoting chasz's comment

themeing is great for the server admin but for the site admin is best to administer from the browser. and thats what CMS's are supposed to do

So please, review the proposed implementation and tell me latter about your decisions on each subject (this issue for the different default values and #302145 for content types discrimination)

Remember: the proposed patch solves this and #302145: Restriction to certain contenttypes?, maybe I should made two different patch, but I wasn't thinking even about literally patches, was just playing around and ended up rewriting the whole module, so it was posted here because it's more relevant to the content types discrimination. Here is the direct link

at #318443: Integration with token (new branch request) you say you don't see the use cases, I won't fight for that argument, but it's some how tight with this one, so I'll try to make the point over here, since token it's too much work to ask for.

from comments on http://www.lullabot.com/articles/drupal_usability_comment_configuration
you can find a similar point of view

COMMENTS SHOULD NEVER HAVE SUBJECTS. Never. Not just no Subject field, but NO SUBJECT AT ALL. A comment is about the post, so the subject is the post. If you provide a field, people put content in the field which is confusing. If you don't provide a field, the subject ends up being the unintelligible first few words. Solution? Comments should be identified by Author and Date, and just not show a subject at all.

shame on me, now I know what you were talking about with other options being possible through theming, just too much time spent on page and node that I completely forgot about comments having their own template

But, without touching a tpl.php file, I wanted to change the comments configuration. Certainly would like to erase the subject once and for all, but found useful the permalink provided on the comment's subject, and didn't wanted to be the author's name nor other thing. The extra options of author and date were included just for the fun of it.
The really needed configuration was the autonumeric on certain content types, for issues or tickets. And there is no need of creating a template for that purpose since it would require to tell somebody that he/she has to create that template with exactly some specific name depending on the content type's machine name and be located on ... far enough from reality.
Don't see the use case yet?

continued here: #318443: Integration with token (new branch request)