roozhou:
I consider the ASS format to be defined by what VSFilter supported and rendered in 2004, not any document, that's simply how things ended up. Extending things won't make anything any better, because a large base of users won't be able to view the effects, picture or whatever the extensions specify.
I hope you can agree with me that subtitles need to be rendered exactly the same regardless of who is viewing them and on what system they are displayed. Just things such as difference in text size and line wrapping can have a major effect on readability, and is in fact one of the failings of most simple, unstyled text formats. (For that purpose, boldface and italics don't really count as styling, by the way.) Any kinds of extensions to a format not supported by and agreed on by every renderer, and supported by the great majority of viewers' software, breaks that assumption.
The real argument here is: Do not use those extensions, because you cannot be sure your viewers will see what you intended for them to see.
As for Kumaji... well I did make a commit a short time ago, but it was really just things I had had sitting for a long time
Aegisub takes up too much of my time.