I have built mini iso images as per links but how I documented it might give you a clue as to why devs are not going to spend that much time learning how to do it?
grub-legacy way is
I have not populated the other folders /bin /etc/ etc...etc. as sidux site actually frowns on any posts that show how to remaster sidux.....and they ask instead ppl to become involved with the sidux project....and I respect their wishes.
grub2 is a wee bit harder for the beginning but easier to mod once you have eltorito images
Making your own eltorito...grub2 image
2) The documents at grub legacy on how to do above is very limited as I am sure you know.
3) AFAIK I have the only wiki on how to do it with grub2....to a sufficient level to allow users build their own isos.
As I know you have built iso images....forgive me while I speak to all readers...
The lack of documentation makes it harder for devs to adopt to grub2.
grub2 does not currently work on ext4.
so in summary...IMHO it is time to read and test using grub legacy or grub2 that is reason
4) Since I know you use grub...a grub iso...has one great advantage over any effort that isolinux can put out....
you can use the grub iso to trouble shoot...or use manual commands to install or repair....depending on whether you populated the iso with sufficient grub legacy or grub2 files.