Why all of this isn't on drupal.org
Those of you familiar with Drupal will know that the drupal.org handbook is the official home of all Drupal-related documentation. You may even also be aware that the handbook has a special section for contributed modules and their documentation.
Recently, a lot of effort has been made to improve the contents and the structure of the handbook. Drupal documentation volunteers are now discouraging people from creating their own external documentation sites, in an effort to centralize the knowledge base of the Drupal community, and to avoid fragmentation, duplication, and inaccessibility of content.
So why isn't all this stuff in the drupal.org handbook?
The answer: the categoryi module is in rather a unique position. The drupal.org handbooks are maintained through the use of the book module. The category module is meant to be a replacement and a better alternative to the book module (as well as to taxonomy). To maintain the category module's documentation using the book module would be hypocritical, and people would be disillusioned and inclined to think: if the module's own documentation doesn't use the module, then who does?
Rather than have people think this, the module eats its own dog food.
As well as the whole 'image issue', there are also a number of practical benefits to having the documentation on a separate site, powered by the category module. The contributed modules section of the handbook is deeply nested, and doesn't accommodate more than a page or two of information for each module very effectively. Any more than that, and a separate site is quite well warranted. Additionally, because of the category module's extra features, other information such as news announcements can be maintained here as well. And don't forget the demo site - that can't go in the Drupal handbook, so other stuff may as well be external, too!
Should Drupal ever switch from having book and taxonomy in core, to having category in core (not happening in the near future, as far as I can tell), there's a possibility that the documentation on this site will move to the drupal.org (category-powered) handbook. But even then, the size of the documentation here may not make it feasible to put it all in the handbook.
The category module does have a page in the handbook: the page tells you to visit this site for more information. So at least users looking in the handbook for information, will find a link to where they can read more.
what i'm really inclined to think
To maintain the categoryi module's documentation using the book module would be hypocritical, and people would be disillusioned and inclined to think: if the module's own documentation doesn't use the module, then who does?
When I'm trying to understand how the category module works, and how to use it, the first thing on my mind is to read the documentation and understand what it says. I couldn't care less how it's maintained and rendered, only about being able to find it, and being able to understand it.
After I've jumped through a hoop or two to find the documentation, and found a page that tells me how disillusioned I would have felt if the documentation had been where I expected it, I'm inclined to start wondering what other hoops I'm going to have to jump through in understanding and using the module.
So yeah, disillusionment, but of a different kind than you anticipated.
Sorry.
Maybe it would be useful to mirror the content...
In the main drupal handbook? Consistency in presentation can be pretty valuable and might make the information more accessible?