Again this content installation stuff was mainly to support my needs for the demo site so I implemented the simplest solution possible to meet those needs. The Html content installer was the first one and the most simple, I didn't need to set any module settings on it for my puposes, but for others like the Flickr module I could not populate any content without setting them. Each feature is different in terms of what it takes to populate it, Image Gallery and WebStore are much more complex for example, I did what was neccessary for my goal and no more and documented it in case others found it useful. Making it complete enough to claim it could be used for site migration would be a very big job and would probably just add a lot of load to support requests considering differences in versions and changes in features over time, it could never really be completely finished and comprehensive and reliable for all features and settings.
If it were an easy change to solve for the html content feature I'd consider doing it just to help you personally, but in general for people making "white label" use of my work I want them to support me financially especially since they are trying to hide the fact that they are using my work from their customers. They can do that but I'm not motivated to work for free to meet their needs.
Maybe someday it will become my own priority to improve the content installers but while I work on my own dime I set my own priorities and that isn't a top one for me right now.
Best,
Joe