I know it may never return, but I really miss the "Gallery of Galleries" page, seeing what other users were doing. Also, I've had trouble with the "generate main gallerie" function, I think because it doesn't like something about very early galleries. So perhaps there could be some improvement to tag certain galleries for inclusion and letting it skip any of those that it has difficulties processing when making the main gallery.
The "Gallery of Galleries" may indeed never return.
About the other problem: You are probably referring to the "Generate main index" feature. I do not know what your problem with the feature is, maybe it is better to discuss the problem in the forum first.